Rotor core structure optimization method for reducing cogging torque and rotor core structure

Abstract

The present invention discloses a rotor core structure optimization method and rotor core structure for reducing cogging torque, which relates to the technical field of motors and their components. The method includes minimizing the cogging torque as an optimization objective function; setting one or more geometric parameters as variables of the objective function, and assigning values ​​to the remaining geometric parameters and setting them as constants of the objective function, performing a parametric sweep on the variables within the set range, and taking the variables corresponding to the minimization of the objective function as the optimal parameters; until all geometric parameters are set as variables of the objective function and a parametric sweep is performed, all the optimal parameters corresponding to the minimization of the objective function are obtained. The present invention mainly solves the problem of how to provide a rotor core structure optimization method for reducing cogging torque; compared with the calculation method of a large number of parameter iterations, the method of the present invention shortens the calculation time, effectively improves the design efficiency of the rotor core structure, and reduces the requirements for computer configuration.

Description

Technical Field

[0001] The present invention relates to the technical field of motors and components thereof, and in particular to a rotor core structure optimization method for reducing cogging torque and a rotor core structure. Background Art

[0002] Electronic water pumps are widely used in automobiles, household appliances and industrial equipment. New energy vehicles, in particular, usually have two or even more electronic water pumps. The electronic water pump is the power source of the entire cooling system of new energy vehicles. The power battery, drive motor, etc. of new energy vehicles all need to rely on electronic water pumps to drive the coolant for circulation cooling. With the rapid development of the new energy vehicle industry, the performance requirements for electronic water pumps are getting higher and higher, and the requirements for noise suppression and vibration suppression of electronic water pumps are also becoming more and more stringent.

[0003] Electronic water pumps usually use permanent magnet synchronous motors as their power source. The structure of their rotor components has a significant impact on the performance of the motor. In addition, the existence of cogging torque is also one of the inherent problems of permanent magnet synchronous motors.

[0004] Some motors used in electronic water pumps have a rotor assembly with a slot-to-pole ratio of 6 slots to 4 poles. Although this rotor assembly can reduce the amount of copper used and thus reduce material costs, it also has a large cogging torque, which will cause large fluctuations in the torque output of the electronic water pump, thereby generating noise and vibration, affecting the performance of the electronic water pump. When this electronic water pump is used in new energy vehicles, it will affect the driving experience.

[0005] In the prior art, methods for reducing cogging torque mainly include:

[0006] 1. On the stator side, there are: adding stator skew slots, opening auxiliary slots on stator teeth, and setting stator slots of unequal widths;

[0007] 2. On the rotor side, there are: setting rotor segmented skew poles, configuring eccentric magnetic poles, and chamfering the permanent magnets.

[0008] However, the above-mentioned method of reducing the cogging torque is mainly aimed at surface-mounted / built-in permanent magnet synchronous motors with a large number of slot poles and a large LCM value (the least common multiple (LCM) of the number of stator slots and the number of poles). In fact, the existing technology has insufficient research on the cogging torque optimization method of the 6-slot 4-pole built-in permanent magnet synchronous motor and the cogging torque optimization method of the general permanent magnet synchronous motor.

[0009] In summary, how to provide a rotor core structure optimization method to reduce the cogging torque has become one of the problems that need to be solved urgently. Summary of the Invention

[0010] The object of the present invention is to provide a rotor core structure optimization method and a rotor core structure for reducing cogging torque, which can effectively reduce the cogging torque and thereby improve the stability of the motor and the electronic water pump.

[0011] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a rotor core structure optimization method for reducing cogging torque, which is used to obtain a rotor core with minimum cogging torque; at the end face or radial cross-section of the rotor core, there are: the rotor core is equally divided into four magnetic poles along the circumferential direction, and each of the magnetic poles is provided with two magnetic tile slots arranged in a "V" shape, and the outer periphery of the rotor core is corresponding to the position of the magnetic poles, and four groups of auxiliary slot groups are configured, and each group of the auxiliary slot groups is provided with two mutually symmetrical auxiliary slots; for each of the auxiliary slots, a number of geometric parameters are defined; the method comprises: minimizing the cogging torque as the optimization objective function; setting one or more of the geometric parameters as variables of the objective function, and assigning values ​​to the remaining geometric parameters The objective function is set as a constant, the variable is parametrically scanned within the set range, and the variable corresponding to the minimization of the objective function is used as the optimal parameter; the optimal parameter obtained in the previous step is set as the constant of the objective function, one or more of the geometric parameters are continuously set as variables of the objective function, and the remaining geometric parameters are assigned values ​​and set as constants of the objective function, the variable is parametrically scanned within the set range, and the variable corresponding to the minimization of the objective function is used as the optimal parameter; until all the geometric parameters are set as variables of the objective function and parametrically scanned, all the optimal parameters corresponding to the minimization of the objective function are obtained; the obtained optimal parameters are applied in the mechanical manufacturing process of the rotor core.

[0012] In the above technical solution, for each auxiliary groove, the following geometric parameters are specifically defined: center distance (X_distance), auxiliary groove angle (X_angle), auxiliary groove radius (Radius), first chamfer (R_rotor1) and second chamfer (R_rotor2).

[0013] In the above technical solution, the center distance (X_distance) is specifically: the distance between the center of the rotor core and the center of the auxiliary slot; the auxiliary slot angle (X_angle) is specifically: the line between the center of the rotor core and the center of the auxiliary slot is defined as the first line, and the axis of the magnetic pole where the auxiliary slot is located is defined as the second line, then the angle between the first line and the second line is the auxiliary slot angle (X_angle); the auxiliary slot radius (Radius) is specifically: the radius of the circle where the auxiliary slot is located; the first chamfer (R_rotor1) is specifically: the chamfer radius of one side of the auxiliary slot that is farther away from the adjacent magnetic tile groove; the second chamfer (R_rotor2) is specifically: the chamfer radius of one side of the auxiliary slot that is closer to the adjacent magnetic tile groove.

[0014] In the above technical solution, the method specifically includes:

[0015] S1. minimizing the cogging torque as an optimization objective function;

[0016] S2. Setting the auxiliary groove radius (Radius) as a variable of the objective function, and assigning values ​​to the center distance (X_distance), the auxiliary groove angle (X_angle), the first chamfered angle (R_rotor1), and the second chamfered angle (R_rotor2) as constants of the objective function, performing a parametric sweep on the auxiliary groove radius (Radius) within a set range, and taking the value of the auxiliary groove radius (Radius) corresponding to the minimization of the objective function as the optimal parameter;

[0017] S3. Setting the optimal parameter of the auxiliary groove radius (Radius) as the constant of the objective function, setting the center distance (X_distance) as the variable of the objective function, and assigning values ​​to the auxiliary groove angle (X_angle), the first chamfered angle (R_rotor1), and the second chamfered angle (R_rotor2) and setting them as constants of the objective function, performing a parametric sweep on the center distance (X_distance) within a set range, and taking the value of the center distance (X_distance) corresponding to the minimization of the objective function as the optimal parameter;

[0018] S4. Setting the optimal parameters of the auxiliary groove radius (Radius) and the center distance (X_distance) as constants of the objective function, setting the auxiliary groove angle (X_angle) as a variable of the objective function, and assigning values ​​to the first chamfered angle (R_rotor1) and the second chamfered angle (R_rotor2) and setting them as constants of the objective function, performing a parametric sweep on the auxiliary groove angle (X_angle) within a set range, and taking the value of the auxiliary groove angle (X_angle) corresponding to the minimization of the objective function as the optimal parameter;

[0019] S5. Setting the optimal parameter of the auxiliary groove radius (Radius), the optimal parameter of the center distance (X_distance), and the optimal parameter of the auxiliary groove angle (X_angle) as constants of the objective function, setting the first chamfered angle (R_rotor1) and the second chamfered angle (R_rotor2) as variables of the objective function, performing parametric scanning and combined optimization within the set range of the first chamfered angle (R_rotor1) and the second chamfered angle (R_rotor2), and taking the values ​​of the first chamfered angle (R_rotor1) and the second chamfered angle (R_rotor2) corresponding to the minimization of the objective function as the optimal parameters;

[0020] S6. Apply the optimal parameters of the center distance (X_distance), the optimal parameters of the auxiliary slot angle (X_angle), the optimal parameters of the auxiliary slot radius (Radius), the optimal parameters of the first chamfer (R_rotor1) and the optimal parameters of the second chamfer (R_rotor2) in the mechanical manufacturing process of the rotor core.

[0021] In the above technical solution, in step S1, minimizing the cogging torque is used as the optimization objective function, specifically: minimizing the peak-to-peak value (pk2pk) of the cogging torque is used as the optimization objective function.

[0022] In the above technical solution, in step S2: the center distance (X_distance) is assigned a value of 21.5 mm, the auxiliary groove angle (X_angle) is assigned a value of 20.5°, the first chamfered angle (R_rotor1) is assigned a value of 5 mm, the second chamfered angle (R_rotor2) is assigned a value of 1.5 mm, and the auxiliary groove radius (Radius) is set in the range of 4.1 mm to 5.5 mm;

[0023] In step S3: the optimal parameter of the auxiliary groove radius (Radius) of 5 mm is set as the constant of the objective function, the auxiliary groove angle (X_angle) is assigned a value of 20.5°, the first chamfered angle (R_rotor1) is assigned a value of 5 mm, the second chamfered angle (R_rotor2) is assigned a value of 1.5 mm, and the center distance (X_distance) is set in the range of 21 mm to 22 mm;

[0024] In step S4, the optimal parameter of the auxiliary groove radius (Radius) of 5 mm and the optimal parameter of the center distance (X_distance) of 21.5 mm are set as constants of the objective function, the first chamfer (R_rotor1) is assigned a value of 5 mm, the second chamfer (R_rotor2) is assigned a value of 1.5 mm, and the setting range of the auxiliary groove angle (X_angle) is 17° to 26°;

[0025] In step S5: the optimal parameter of the auxiliary groove radius (Radius) is 5mm, the optimal parameter of the center distance (X_distance) is 21.5mm, and the optimal parameter of the auxiliary groove angle (X_angle) is 20.5°, which is set as the constant of the objective function. The setting range of the first chamfer (R_rotor1) is 1mm~10mm, and the setting range of the second chamfer (R_rotor2) is 0.5mm~7mm.

[0026] In the above technical solution, in step S2: after performing a parametric sweep on the auxiliary groove radius (Radius), the value of the auxiliary groove radius (Radius) corresponding to the minimization of the objective function is 5 mm;

[0027] In step S3: after performing a parametric sweep on the circle center distance (X_distance), the value of the circle center distance (X_distance) corresponding to the minimization of the objective function is 21.5 mm;

[0028] In step S4: after performing a parametric sweep on the auxiliary groove angle (X_angle), the value of the auxiliary groove angle (X_angle) corresponding to the minimization of the objective function is 20.5°;

[0029] In step S5: after parametric scanning and combined optimization of the first chamfer (R_rotor1) and the second chamfer (R_rotor2), the value of the first chamfer (R_rotor1) corresponding to the minimization of the objective function is 4.5 mm, and the value of the second chamfer (R_rotor2) is 2 mm.

[0030] In the above technical solution, the pole arc angle of each magnetic pole of the rotor core is A_angle, and the auxiliary slot angle (X_angle) is limited to: 2*X_angle<A_angle.

[0031] A rotor core structure comprises at least a rotor core; the rotor core structure adopts the above-mentioned rotor core structure optimization method for reducing cogging torque.

[0032] In the above technical solution, at the end face or radial cross-section of the rotor core, there are: the rotor core is equally divided into four magnetic poles along the circumferential direction, and each of the magnetic poles is provided with two magnetic tile grooves arranged in a "V" shape, and the outer circumference of the rotor core is corresponding to the position of the magnetic pole, and four groups of auxiliary slot groups are provided, and each group of the auxiliary slot groups is provided with two mutually symmetrical auxiliary slots; for each of the auxiliary slots, the following geometric parameters are specifically defined: center distance (X_distance): the distance between the center of the rotor core and the center of the auxiliary slot; auxiliary slot angle (X_angle): the line connecting the center of the rotor core and the center of the auxiliary slot is defined as the first line, and the axis of the magnetic pole where the auxiliary slot is located is defined as the second line, then the first line and the The angle of the second line is the auxiliary groove angle (X_angle); the auxiliary groove radius (Radius): the radius of the circle in which the auxiliary groove is located; the first chamfer (R_rotor1): the chamfer radius of the auxiliary groove on one side that is farther away from the adjacent magnetic tile groove; the second chamfer (R_rotor2): the chamfer radius of the auxiliary groove on one side that is closer to the adjacent magnetic tile groove; the value of the center distance (X_distance) is 21.5mm, the value of the auxiliary groove radius (Radius) is 5mm, the value of the auxiliary groove angle (X_angle) is 20.5°, the value of the first chamfer (R_rotor1) is 4.5mm, and the value of the second chamfer (R_rotor2) is 2mm.

[0033] Compared with the prior art, the beneficial effects of the present invention are: the rotor core structure optimization method and rotor core structure for reducing the cogging torque of the present invention define several geometric parameters that affect the cogging torque at the auxiliary slots of the rotor core, and take the minimization of the cogging torque as the optimization objective function, and then use each geometric parameter as the variable of the objective function one by one. After several parametric scans, the optimal parameters of each geometric parameter are obtained. The obtained optimal parameters can be applied in the mechanical manufacturing process of the rotor core, thereby manufacturing a rotor core structure with the minimum cogging torque, so as to improve the performance and stability of the motor / electronic water pump. Compared with the calculation method of a large number of parameter iterations, the method of the present invention shortens the calculation time, effectively improves the design efficiency of the rotor core structure, and reduces the requirements for computer configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a structural view of the end face / radial cross section of the rotor core in the present invention.

[0035] Figure 2 This is a waveform diagram showing the cogging torque changing over time when the auxiliary slot radius (Radius) is used as the variable of the objective function.

[0036] Figure 3 This is a waveform diagram showing the peak-to-peak value of the cogging torque (pk2pk) changing with the auxiliary groove radius (Radius).

[0037] Figure 4 This is a waveform graph showing how the cogging torque changes over time when the center distance (X_distance) is used as the variable in the objective function.

[0038] Figure 5 This is a waveform diagram showing the peak-to-peak value of the cogging torque (pk2pk) changing with the center distance (X_distance).

[0039] Figure 6 This is a waveform diagram showing the cogging torque changing over time when the auxiliary slot angle (X_angle) is used as the variable of the objective function.

[0040] Figure 7 This is a waveform diagram showing how the peak-to-peak value of the cogging torque (pk2pk) changes with the auxiliary slot angle (X_angle).

[0041] Figure 8 It is a three-dimensional cloud diagram of the peak-to-peak value of the cogging torque (pk2pk) changing with the first fillet angle (R_rotor1) and the second fillet angle (R_rotor2).

[0042] The figures are marked as follows: 1. rotor core; 2. magnetic pole; 3. magnetic shoe slot; 4. auxiliary slot; 5. first wire; 6. second wire. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] This embodiment provides a rotor core structure optimization method for reducing cogging torque, which can be implemented during the structural design stage of the rotor core to obtain a rotor core with minimum cogging torque, thereby improving the stability of the motor / electronic water pump using the rotor core.

[0045] First of all, it should be noted that cogging torque is the torque generated by the interaction between the permanent magnets and the stator core when the permanent magnet motor windings are not energized. It is caused by the tangential component of the interaction force between the permanent magnets and the armature teeth. It is one of the issues that must be considered and resolved in the design and manufacture of permanent magnet motors. When the cogging torque is optimized to a minimum, the impact on the performance and stability of the permanent magnet motor is also minimized. This embodiment aims to provide a rotor core structure optimization method for reducing cogging torque. By optimizing the structure of the rotor core, the cogging torque is minimized.

[0046] The rotor core 1 in this embodiment is specifically a 6-slot 4-pole structure, which is formed by axially stacking a number of magnetic steel materials (such as silicon steel sheets). Its end face / radial cross-section structure is as follows: Figure 1 As shown, at the end face or radial cross section of the rotor core 1, there are:

[0047] The rotor core 1 is equally divided into four magnetic poles 2 along the circumferential direction, and each magnetic pole 2 is provided with two magnetic tile grooves 3 arranged in a "V" shape. The "V"-shaped opening formed by the two magnetic tile grooves 3 faces the outside of the rotor core 1 (backwards from the center of the rotor core 1), and the outer circumference of the rotor core 1 is corresponding to the position of the magnetic poles 2, and four groups of auxiliary slot groups are configured, and each group of auxiliary slot groups is provided with two mutually symmetrical auxiliary slots 4. In fact, the main body of each auxiliary slot 4 is an inwardly concave arc shape at the end face or radial cross-section of the rotor core 1.

[0048] For each auxiliary slot 4, a number of geometric parameters are defined, wherein the geometric parameters are actually mechanical parameters such as size, angle and radius related to the auxiliary slot 4, which can be directly applied in the mechanical manufacturing process of the rotor core 1 to manufacture the auxiliary slot 4 with corresponding geometric parameters.

[0049] The method includes:

[0050] Minimizing the cogging torque is used as the optimization objective function;

[0051] One or more of the geometric parameters are set as variables of the objective function, and the remaining geometric parameters are assigned values ​​and set as constants of the objective function. The variables are parametrically scanned within the set range, and the variables corresponding to the minimization of the objective function are taken as the optimal parameters.

[0052] The optimal parameters obtained in the previous step are set as constants of the objective function. One or more geometric parameters are then set as variables of the objective function. The remaining geometric parameters are assigned values ​​and set as constants of the objective function. A parametric sweep is performed on the variables within the set range. The variable corresponding to the minimum objective function is taken as the optimal parameter.

[0053] Until all geometric parameters are set as variables of the objective function and a parametric sweep is performed, all the optimal parameters corresponding to the minimization of the objective function are obtained;

[0054] The obtained optimal parameters are applied in the mechanical manufacturing process of the rotor core 1.

[0055] Specifically, for each auxiliary groove 4 , the following geometric parameters are specifically defined: center distance (X_distance), auxiliary groove angle (X_angle), auxiliary groove radius (Radius), first chamfered corner (R_rotor1) and second chamfered corner (R_rotor2).

[0056] See also Figure 1 The center distance (X_distance) is specifically the distance between the center of the rotor core 1 and the center of the auxiliary slot 4;

[0057] The auxiliary slot angle (X_angle) is specifically defined as follows: the line connecting the center of the rotor core 1 and the center of the auxiliary slot 4 is defined as the first line 5, and the axis of the magnetic pole 2 where the auxiliary slot 4 is located is defined as the second line 6. The angle between the first line 5 and the second line 6 is the auxiliary slot angle (X_angle);

[0058] The auxiliary groove radius (Radius) is specifically: the radius of the circle where the auxiliary groove 4 is located;

[0059] The first rounded corner (R_rotor1) is specifically: the rounded corner radius of the auxiliary slot 4, which is farther away from the adjacent magnetic shoe slot 3;

[0060] The second rounded corner (R_rotor2) is specifically the rounded corner radius of the auxiliary slot 4 on one side closer to the adjacent magnetic shoe slot 3.

[0061] See also Figure 1 , each magnetic pole 2 of the rotor core 1 has a pole arc angle of A_angle, and the auxiliary slot angle (X_angle) is limited to: 2*X_angle<A_angle.

[0062] With the above-mentioned restriction, it is ensured that the auxiliary slot 4 is located within the magnetic field range of the magnetic pole 2 .

[0063] More specifically, the method includes:

[0064] S1, minimizing the cogging torque as the optimization objective function;

[0065] S2. Set the auxiliary groove radius (Radius) as the variable of the objective function, and assign values ​​to the center distance (X_distance), auxiliary groove angle (X_angle), first chamfer angle (R_rotor1), and second chamfer angle (R_rotor2) as constants of the objective function. Perform a parametric sweep on the auxiliary groove radius (Radius) within the set range, and select the value of the auxiliary groove radius (Radius) that minimizes the objective function as the optimal parameter.

[0066] S3. Set the optimal parameter of the auxiliary groove radius (Radius) as the constant of the objective function, set the center distance (X_distance) as the variable of the objective function, and assign values ​​to the auxiliary groove angle (X_angle), the first chamfer (R_rotor1), and the second chamfer (R_rotor2) and set them as constants of the objective function. Perform a parametric sweep on the center distance (X_distance) within the set range, and take the value of the center distance (X_distance) that minimizes the objective function as the optimal parameter;

[0067] S4. Setting the optimal parameters of the auxiliary groove radius (Radius) and the center distance (X_distance) as constants of the objective function, setting the auxiliary groove angle (X_angle) as a variable of the objective function, and assigning values ​​to the first chamfered angle (R_rotor1) and the second chamfered angle (R_rotor2) and setting them as constants of the objective function, performing a parametric sweep on the auxiliary groove angle (X_angle) within a set range, and taking the value of the auxiliary groove angle (X_angle) corresponding to the minimization of the objective function as the optimal parameter;

[0068] S5. Setting the optimal parameters of the auxiliary groove radius (Radius), the optimal parameters of the center distance (X_distance), and the optimal parameters of the auxiliary groove angle (X_angle) as constants of the objective function, setting the first chamfer angle (R_rotor1) and the second chamfer angle (R_rotor2) as variables of the objective function, performing parametric sweep and combined optimization within the set range of the first chamfer angle (R_rotor1) and the second chamfer angle (R_rotor2), and taking the values ​​of the first chamfer angle (R_rotor1) and the second chamfer angle (R_rotor2) corresponding to the minimization of the objective function as the optimal parameters;

[0069] S6. Apply the optimal parameters of the center distance (X_distance), the optimal parameters of the auxiliary slot angle (X_angle), the optimal parameters of the auxiliary slot radius (Radius), the optimal parameters of the first chamfer (R_rotor1) and the optimal parameters of the second chamfer (R_rotor2) to the mechanical manufacturing process of the rotor core 1.

[0070] In step S1 , the cogging torque is minimized as the optimization objective function, specifically, the peak-to-peak value (pk2pk) of the cogging torque is minimized as the optimization objective function.

[0071] The cogging torque is directional, so the cogging torque in all directions should be minimized. Therefore, minimizing the peak-to-peak value (pk2pk) of the cogging torque is used as the optimization objective function to minimize the cogging torque in all directions as much as possible.

[0072] More specifically, in step S2: the center distance (X_distance) is assigned a value of 21.5 mm, the auxiliary groove angle (X_angle) is assigned a value of 20.5°, the first rounded angle (R_rotor1) is assigned a value of 5 mm, the second rounded angle (R_rotor2) is assigned a value of 1.5 mm, and the auxiliary groove radius (Radius) is set in the range of 4.1 mm to 5.5 mm; Figure 2 and Figure 3 As shown in the figure, after parametric scanning of the auxiliary groove radius (Radius), the value of the auxiliary groove radius (Radius) corresponding to the minimization of the objective function is 5 mm. This value is the optimal parameter of the auxiliary groove radius (Radius). At this time, the peak-to-peak value (pk2pk) of the cogging torque has a minimum value of 0.0057 Nm.

[0073] More specifically, in step S3: the optimal parameter of the auxiliary groove radius (Radius) is set as 5mm as the constant of the objective function, the auxiliary groove angle (X_angle) is assigned to 20.5°, the first chamfer (R_rotor1) is assigned to 5mm, the second chamfer (R_rotor2) is assigned to 1.5mm, and the center distance (X_distance) is set in the range of 21mm to 22mm; Figure 4 and Figure 5 As shown in the figure, after performing a parametric sweep on the center distance (X_distance), the value of the center distance (X_distance) corresponding to the objective function minimization is 21.5 mm. This value is the optimal parameter for the center distance (X_distance). At this time, the peak-to-peak value of the cogging torque (pk2pk) reaches a minimum value of 0.0057 Nm.

[0074] More specifically, in step S4: the optimal parameter of the auxiliary groove radius (Radius) is 5mm and the optimal parameter of the center distance (X_distance) is 21.5mm as constants of the objective function, the first chamfer (R_rotor1) is assigned a value of 5mm, the second chamfer (R_rotor2) is assigned a value of 1.5mm, and the setting range of the auxiliary groove angle (X_angle) is 17° to 26°; Figure 6 and Figure 7 As shown in the figure, after parametric scanning of the auxiliary slot angle (X_angle), the value of the auxiliary slot angle (X_angle) corresponding to the minimization of the objective function is 20.5°, which is the optimal parameter of the auxiliary slot angle (X_angle). At this time, the peak-to-peak value (pk2pk) of the cogging torque has a minimum value of 0.0057 Nm.

[0075] More specifically, in step S5: the optimal parameter of the auxiliary groove radius (Radius) is 5mm, the optimal parameter of the center distance (X_distance) is 21.5mm, and the optimal parameter of the auxiliary groove angle (X_angle) is 20.5°, which is set as the constant of the objective function. The setting range of the first chamfer (R_rotor1) is 1mm to 10mm, and the setting range of the second chamfer (R_rotor2) is 0.5mm to 7mm; as shown in Tables 1-1, 1-2 and Figure 8 As shown in the figure, after parametric scanning and combined optimization of the first chamfer (R_rotor1) and the second chamfer (R_rotor2), the value of the first chamfer (R_rotor1) corresponding to the minimization of the objective function is 4.5 mm, and the value of the second chamfer (R_rotor2) is 2 mm. These values ​​are the optimal parameters of the first chamfer (R_rotor1) and the second chamfer (R_rotor2). At this time, the peak-to-peak value (pk2pk) of the cogging torque has a minimum value of 4.95354 mNm.

[0076] In Table 1-1 and Table 1-2, the units of the first chamfer angle (R_rotor1) and the second chamfer angle (R_rotor2) are both mm, and the unit of the peak-to-peak value of the cogging torque (pk2pk) is mNm.

[0077]

[0078] Table 1-1 One of the discrete data tables showing the peak-to-peak value of the cogging torque (pk2pk) as a function of the first rounding angle (R_rotor1) and the second rounding angle (R_rotor2)

[0079]

[0080] Table 1-2 Peak-to-peak value of cogging torque (pk2pk) with the first fillet angle (R_rotor1) and the second fillet angle

[0081] (R_rotor2) Discrete data table of changes 2

[0082] It can be understood that the rotor core structure optimization method for reducing the slot torque of this embodiment can complete the parametric scanning of the center distance (X_distance), auxiliary slot angle (X_angle), auxiliary slot radius (Radius), first chamfer (R_rotor1) and second chamfer (R_rotor2) in electromagnetic software such as Ansys Electronics or Ansoft Maxwell, so as to obtain the optimal parameters and the corresponding peak-to-peak value of the slot torque (pk2pk).

[0083] See also Figure 1 This embodiment also provides a rotor core structure, which at least includes a rotor core 1; it applies the above-mentioned rotor core structure optimization method for reducing the cogging torque.

[0084] The rotor core 1 in this embodiment is specifically a 6-slot 4-pole structure, which is formed by axially stacking a number of magnetic steel materials (such as silicon steel sheets). Its end face / radial cross-section structure is as follows: Figure 1 As shown, at the end face or radial cross section of the rotor core 1, there are:

[0085] The rotor core 1 is equally divided into four magnetic poles 2 along the circumferential direction, and each magnetic pole 2 is provided with two magnetic tile grooves 3 arranged in a "V" shape. The "V"-shaped opening formed by the two magnetic tile grooves 3 faces the outside of the rotor core 1 (backwards from the center of the rotor core 1), and the outer circumference of the rotor core 1 is corresponding to the position of the magnetic poles 2, and four groups of auxiliary slot groups are configured, and each group of auxiliary slot groups is provided with two mutually symmetrical auxiliary slots 4. In fact, the main body of each auxiliary slot 4 is an inwardly concave arc shape at the end face or radial cross-section of the rotor core 1.

[0086] For each auxiliary slot 4, the following geometric parameters are specifically defined:

[0087] Center distance (X_distance): the distance between the center of the rotor core 1 and the center of the auxiliary slot 4;

[0088] Auxiliary slot angle (X_angle): The line connecting the center of the rotor core 1 and the center of the auxiliary slot 4 is defined as the first line 5, and the axis of the magnetic pole 2 where the auxiliary slot 4 is located is defined as the second line 6. The angle between the first line 5 and the second line 6 is the auxiliary slot angle (X_angle);

[0089] Auxiliary slot radius (Radius): The radius of the circle where the auxiliary slot 4 is located;

[0090] First fillet (R_rotor1): the fillet radius of the auxiliary slot 4 on the side further away from the adjacent magnetic shoe slot 3;

[0091] Second rounded corner (R_rotor2): the rounded corner radius of the auxiliary slot 4 on one side closer to the adjacent magnetic shoe slot 3 .

[0092] The center distance (X_distance) is 21.5 mm, the auxiliary groove radius (Radius) is 5 mm, the auxiliary groove angle (X_angle) is 20.5°, the first fillet (R_rotor1) is 4.5 mm, and the second fillet (R_rotor2) is 2 mm. At this time, the peak-to-peak value of the cogging torque (pk2pk) reaches a minimum value of 4.95354 mNm.

[0093] The rotor core structure optimization method and rotor core structure for reducing cogging torque of this embodiment define several geometric parameters that affect the cogging torque at the auxiliary slots of the rotor core, minimize the cogging torque as the optimization objective function, and then use each geometric parameter as a variable of the objective function one by one. After several parametric scans, the optimal parameters of each geometric parameter are obtained. The obtained optimal parameters can be applied in the mechanical manufacturing process of the rotor core, thereby manufacturing a rotor core structure with minimal cogging torque, so as to improve the performance and stability of the motor / electronic water pump. Compared with the calculation method of a large number of parameter iterations, the method of this embodiment shortens the calculation time, effectively improves the design efficiency of the rotor core structure, and reduces the requirements for computer configuration.

[0094] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A rotor core structure optimization method for reducing cogging torque, for obtaining a rotor core with minimum cogging torque; characterized in that: At the end face or radial cross section of the rotor core, there are: The rotor core is equally divided into four magnetic poles along the circumferential direction, and each magnetic pole is provided with two magnetic shoe slots arranged in a "V" shape. In addition, the outer circumference of the rotor core is provided with four auxiliary slot groups corresponding to the positions of the magnetic poles, and each auxiliary slot group is provided with two mutually symmetrical auxiliary slots. For each of the auxiliary slots, a number of geometric parameters are defined; The method includes: minimizing the cogging torque as an optimization objective function; Setting one or more of the geometric parameters as variables of the objective function, and assigning values ​​to the remaining geometric parameters as constants of the objective function, performing a parametric sweep on the variables within a set range, and taking the variables corresponding to the minimization of the objective function as the optimal parameters; Setting the optimal parameters obtained in the previous step as constants of the objective function, continuing to set one or more of the geometric parameters as variables of the objective function, and assigning values ​​to the remaining geometric parameters and setting them as constants of the objective function, performing a parametric sweep on the variables within a set range, and taking the variables corresponding to the minimization of the objective function as the optimal parameters; until all the geometric parameters are set as variables of the objective function and after performing parametric scanning, all the optimal parameters corresponding to the minimization of the objective function are obtained; Applying the obtained optimal parameters to the mechanical manufacturing process of the rotor core; For each auxiliary slot, the following geometric parameters are specifically defined: Center distance (X_distance), auxiliary groove angle (X_angle), auxiliary groove radius (Radius), first rounded corner (R_rotor1), and second rounded corner (R_rotor2); The center distance (X_distance) is specifically: the distance between the center of the rotor core and the center of the auxiliary slot; The auxiliary slot angle (X_angle) is specifically defined as follows: a line connecting the center of the rotor core and the center of the auxiliary slot is defined as a first line, an axis of the magnetic pole where the auxiliary slot is located is defined as a second line, and an angle between the first line and the second line is defined as the auxiliary slot angle (X_angle); The auxiliary groove radius (Radius) is specifically: the radius of the circle where the auxiliary groove is located; The first rounded corner (R_rotor1) is specifically: the rounded corner radius of one side of the auxiliary groove that is further away from the adjacent magnetic shoe groove; The second rounded corner (R_rotor2) is specifically: the rounded corner radius of one side of the auxiliary groove closer to the adjacent magnetic shoe groove; The method specifically includes: S1. minimizing the cogging torque as an optimization objective function; S2. Setting the auxiliary groove radius (Radius) as a variable of the objective function, and assigning values ​​to the center distance (X_distance), the auxiliary groove angle (X_angle), the first chamfered angle (R_rotor1), and the second chamfered angle (R_rotor2) as constants of the objective function, performing a parametric sweep on the auxiliary groove radius (Radius) within a set range, and taking the value of the auxiliary groove radius (Radius) corresponding to the minimization of the objective function as the optimal parameter; S3. Setting the optimal parameter of the auxiliary groove radius (Radius) as the constant of the objective function, setting the center distance (X_distance) as the variable of the objective function, and assigning values ​​to the auxiliary groove angle (X_angle), the first chamfered angle (R_rotor1), and the second chamfered angle (R_rotor2) and setting them as constants of the objective function, performing a parametric sweep on the center distance (X_distance) within a set range, and taking the value of the center distance (X_distance) corresponding to the minimization of the objective function as the optimal parameter; S4. Setting the optimal parameters of the auxiliary groove radius (Radius) and the center distance (X_distance) as constants of the objective function, setting the auxiliary groove angle (X_angle) as a variable of the objective function, and assigning values ​​to the first chamfered angle (R_rotor1) and the second chamfered angle (R_rotor2) and setting them as constants of the objective function, performing a parametric sweep on the auxiliary groove angle (X_angle) within a set range, and taking the value of the auxiliary groove angle (X_angle) corresponding to the minimization of the objective function as the optimal parameter; S5. Setting the optimal parameter of the auxiliary groove radius (Radius), the optimal parameter of the center distance (X_distance), and the optimal parameter of the auxiliary groove angle (X_angle) as constants of the objective function, setting the first chamfered angle (R_rotor1) and the second chamfered angle (R_rotor2) as variables of the objective function, performing parametric scanning and combined optimization within the set range of the first chamfered angle (R_rotor1) and the second chamfered angle (R_rotor2), and taking the values ​​of the first chamfered angle (R_rotor1) and the second chamfered angle (R_rotor2) corresponding to the minimization of the objective function as the optimal parameters; S6. Apply the optimal parameters of the center distance (X_distance), the optimal parameters of the auxiliary slot angle (X_angle), the optimal parameters of the auxiliary slot radius (Radius), the optimal parameters of the first chamfer (R_rotor1) and the optimal parameters of the second chamfer (R_rotor2) in the mechanical manufacturing process of the rotor core.

2. The rotor core structure optimization method for reducing cogging torque according to claim 1, characterized in that: In step S1, the cogging torque is minimized as the optimization objective function, specifically: Minimizing the peak-to-peak value (pk2pk) of the cogging torque is used as the optimization objective function.

3. The rotor core structure optimization method for reducing cogging torque according to claim 1, characterized in that: In step S2: The center distance (X_distance) is set to 21.5 mm, the auxiliary groove angle (X_angle) is set to 20.5°, the first chamfered angle (R_rotor1) is set to 5 mm, the second chamfered angle (R_rotor2) is set to 1.5 mm, and the auxiliary groove radius (Radius) is set in the range of 4.1 mm to 5.5 mm; In step S3: The optimal parameter of the auxiliary groove radius (Radius) is set as 5 mm as the constant of the objective function, the auxiliary groove angle (X_angle) is assigned a value of 20.5°, the first chamfered angle (R_rotor1) is assigned a value of 5 mm, the second chamfered angle (R_rotor2) is assigned a value of 1.5 mm, and the center distance (X_distance) is set in the range of 21 mm to 22 mm; In step S4: The optimal parameters of the auxiliary groove radius (Radius) of 5 mm and the optimal parameter of the center distance (X_distance) of 21.5 mm are set as constants of the objective function, the first chamfer angle (R_rotor1) is assigned a value of 5 mm, the second chamfer angle (R_rotor2) is assigned a value of 1.5 mm, and the setting range of the auxiliary groove angle (X_angle) is 17° to 26°; In step S5: The optimal parameter of the auxiliary groove radius (Radius) is 5mm, the optimal parameter of the center distance (X_distance) is 21.5mm, and the optimal parameter of the auxiliary groove angle (X_angle) is 20.5°, which is set as the constants of the objective function. The setting range of the first chamfer (R_rotor1) is 1mm~10mm, and the setting range of the second chamfer (R_rotor2) is 0.5mm~7mm.

4. The rotor core structure optimization method for reducing cogging torque according to claim 3, characterized in that: In step S2: After performing a parametric sweep on the auxiliary groove radius (Radius), the value of the auxiliary groove radius (Radius) corresponding to the minimization of the objective function is 5 mm; In step S3: After performing a parametric sweep on the center distance (X_distance), the value of the center distance (X_distance) corresponding to the minimization of the objective function is 21.5 mm; In step S4: After performing a parametric sweep on the auxiliary groove angle (X_angle), the value of the auxiliary groove angle (X_angle) corresponding to the minimization of the objective function is 20.5°; In step S5: After parametric scanning and combined optimization of the first chamfer (R_rotor1) and the second chamfer (R_rotor2), the value of the first chamfer (R_rotor1) corresponding to the minimization of the objective function is 4.5 mm, and the value of the second chamfer (R_rotor2) is 2 mm.

5. The rotor core structure optimization method for reducing cogging torque according to claim 1, characterized in that: The pole arc angle of each magnetic pole of the rotor core is A_angle, and the auxiliary slot angle (X_angle) is limited to: 2*X_angle<A_angle.

6. A rotor core structure, comprising at least a rotor core; characterized in that: The rotor core structure optimization method for reducing cogging torque described in any one of claims 1 to 5 is applied.

7. The rotor core structure according to claim 6, characterized in that: At the end face or radial cross section of the rotor core, there are: The rotor core is equally divided into four magnetic poles along the circumferential direction, and each magnetic pole is provided with two magnetic shoe slots arranged in a "V" shape. In addition, the outer circumference of the rotor core is provided with four auxiliary slot groups corresponding to the positions of the magnetic poles, and each auxiliary slot group is provided with two mutually symmetrical auxiliary slots. For each auxiliary slot, the following geometric parameters are specifically defined: Center distance (X_distance): the distance between the center of the rotor core and the center of the auxiliary slot; Auxiliary slot angle (X_angle): The line connecting the center of the rotor core and the center of the auxiliary slot is defined as the first line, and the axis of the magnetic pole where the auxiliary slot is located is defined as the second line. The angle between the first line and the second line is the auxiliary slot angle (X_angle); Auxiliary groove radius (Radius): the radius of the circle where the auxiliary groove is located; First rounded corner (R_rotor1): the rounded corner radius of the auxiliary slot, which is farther away from the adjacent magnetic shoe slot; Second fillet (R_rotor2): the fillet radius of the auxiliary slot, closer to the adjacent magnetic shoe slot; The value of the center distance (X_distance) is 21.5 mm, the value of the auxiliary groove radius (Radius) is 5 mm, the value of the auxiliary groove angle (X_angle) is 20.5°, the value of the first chamfered angle (R_rotor1) is 4.5 mm, and the value of the second chamfered angle (R_rotor2) is 2 mm.

Images