A multi-dimensional electromechanical coupling dynamics modeling and analysis method for an outer rotor wheel hub motor

Abstract

This invention relates to a method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor, comprising: constructing a six-degree-of-freedom vertical dynamic model (VDMAD) considering the axial deflection of the stator and rotor; constructing a multidimensional eccentric unbalanced electromagnetic force model (MUEF); and constructing a motor control model; performing transient electromechanical coupling on the VDMAD, MUEF, and motor control models to establish a multidimensional eccentric electromechanical coupling model (MDEEC); inputting the vehicle axle load and road surface roughness as external excitations into the MDEEC; and obtaining the transient multidimensional eccentricity, unbalanced electromagnetic force, and vibration characteristics of the external rotor hub motor through closed-loop solution of the dynamic equations. Compared with existing technologies, this invention can accurately characterize the axial structural features and transient multidimensional eccentricity coupling effect of the external rotor hub motor, accurately solve the dynamic characteristics of the external rotor hub motor under coupled excitation, and improve the model prediction accuracy.

Description

Technical Field

[0001] This invention relates to the field of modeling and analysis technology for external rotor hub motors, and in particular to a method for multidimensional electromechanical coupling dynamics modeling and analysis of external rotor hub motors. Background Technology

[0002] As a core component of the powertrain system for distributed drive electric vehicles, the external rotor hub motor boasts advantages such as a short drive chain and flexible power distribution, making it an important development direction for new energy vehicles. However, the external rotor hub motor adds unsprung mass, and under the coupling effects of vehicle axle load, road surface roughness, and unbalanced electromagnetic forces, a significant stator-rotor eccentricity phenomenon occurs. This leads to deterioration of the NVH characteristics of the external rotor hub motor and reduced ride comfort, which has become a key issue restricting the large-scale application of external rotor hub motors.

[0003] In existing technologies, researchers have conducted relevant studies on the vertical dynamic characteristics of external rotor hub motors, proposing vertical electromechanical coupling dynamic models with 2, 3, and 4 degrees of freedom. However, many technical shortcomings still exist. 1. Traditional dynamic models oversimplify the axial structural features of external rotor hub motors, fail to consider the axial deflection degrees of freedom of the stator and rotor, and treat eccentricity only as a constant parameter of the radial single dimension. This makes it impossible to characterize the coupling relationship between radial and axial eccentricity, and also impossible to accurately calculate transient multidimensional eccentricity. 2. Existing unbalanced electromagnetic force models are mostly calculated using the equivalent stiffness method or table lookup method, which ignores the transient higher-order electromagnetic force components and does not take into account the static eccentricity generated by the vehicle axle load. Therefore, they cannot reflect the coupled excitation effect of the vehicle axle load, road surface roughness and unbalanced electromagnetic force. 3. Traditional electromechanical coupling models do not consider axial angular stiffness, the axial distribution of the center of mass and load-bearing positions of each component, and cannot analyze the coupling effect of axial deflection and vertical vibration, resulting in an inaccurate reflection of the actual dynamic characteristics of the external rotor hub motor.

[0004] In summary, existing dynamic models of external rotor hub motors suffer from low modeling accuracy, failure to consider transient multidimensional eccentric coupling, and insufficient structural feature representation, thus failing to provide accurate theoretical guidance for the structural design and NVH optimization of external rotor hub motors. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a multidimensional electromechanical coupling dynamics modeling and analysis method for external rotor hub motors. This method can accurately characterize the axial structural features and transient multidimensional eccentric coupling effect of external rotor hub motors, accurately solve the dynamic characteristics of external rotor hub motors under coupled excitation, and improve the model prediction accuracy.

[0006] The objective of this invention can be achieved through the following technical solution: a multidimensional electromechanical coupling dynamics modeling and analysis method for an external rotor hub motor, comprising: A six-degree-of-freedom vertical dynamics model considering Axial Deflection (VDMAD) and an unbalanced electromagnetic force model with multi-dimension eccentricity (MUEF) were constructed respectively. A motor control model is constructed to provide electromagnetic force calculation input for MUEF and speed input for road roughness excitation for VDMAD; Transient electromechanical coupling was performed on VDMAD, MUEF, and motor control models to establish a multi-dimensional eccentricity electromechanical coupling model (MDEEC). The vehicle axle load and road surface roughness were used as external excitation inputs to MDEEC. The transient multi-dimensional eccentricity, unbalanced electromagnetic force, and vibration characteristics of the outer rotor hub motor were obtained by solving the dynamic equations in a closed loop.

[0007] Furthermore, the process of constructing the six-degree-of-freedom vertical dynamic model VDMAD, which considers the axial deflection of the stator and rotor, includes: Considering the axial structural characteristics of the external rotor hub motor, a six-degree-of-freedom vertical dynamic model (VDMAD) is constructed, including 1 / 4 of the sprung mass vertical degree of freedom, stator vertical and axial deflection degrees of freedom, rotor vertical and axial deflection degrees of freedom, and tire vertical degree of freedom. This model introduces the axial angular stiffness and damping coefficient of the suspension, hub bearing, and tire, clarifies the centroid positions of the stator and rotor, and the axial coordinates of the load-bearing positions of the suspension, hub bearing, seals, and rim. The radial stiffness and angular stiffness of the hub bearing are identified through a fixture loading test. The VDMAD dynamic equation is established by combining the d'Alembert principle. The vehicle axle load and road surface roughness are used as external excitations to calculate transient multidimensional eccentricity.

[0008] Furthermore, the transient multidimensional eccentricity includes a static component generated by the vehicle axle load, and a dynamic component generated by the coupling excitation of road surface roughness and unbalanced electromagnetic force.

[0009] Furthermore, the process of calculating transient multidimensional eccentricity includes: The static components are obtained by solving the VDMAD dynamic equations with the dynamic excitation set to zero. The dynamic components are obtained by numerically solving the dynamic response of VDMAD using the state-space method.

[0010] Furthermore, the process of constructing the multidimensional eccentric unbalanced electromagnetic force model MUEF includes: The transient multidimensional eccentricity of the external rotor hub motor is decomposed into transient radial eccentricity and axial eccentricity, both of which contain static and dynamic components. The relative permeability of the air gap is corrected using radial eccentricity correction coefficients and axial eccentricity correction coefficients; The radial and tangential electromagnetic forces in the air gap are calculated based on the Maxwell stress tensor. The circumferentially distributed electromagnetic forces are integrated along the axial direction and decomposed into unbalanced vertical forces and axial deflection torques acting on the VDMAD, thus completing the construction of the MUEF.

[0011] Furthermore, the radial eccentricity correction coefficient is specifically a function based on the stator and rotor center offset, the initial length of the air gap, and the circumferential angle; The axial eccentricity correction coefficient is specifically a function based on the axial deflection angle of the stator and rotor and the axial length of the air gap.

[0012] Furthermore, the Maxwell stress tensor is specifically calculated by combining the magnetic flux density of the permanent magnet, the magnetic flux density of the armature, and the complex relative permeability of the air gap of the stator slot.

[0013] Furthermore, the process of constructing the motor control model includes: Based on the rotor field-oriented motor control strategy of permanent magnet synchronous motor, a motor control model for external rotor hub motor is constructed. The target torque and target speed are input, and the feedback of transient load torque is considered. The output is three-phase current, motor angle and actual speed consistent with the actual working conditions. Among them, the three-phase current and motor angle provide input parameters for electromagnetic force calculation of MUEF, and the actual speed provides input parameters for road roughness excitation modeling of VDMAD.

[0014] Furthermore, the process of transiently electromechanical coupling VDMAD, MUEF, and the motor control model includes: The dynamic response of VDMAD is used to provide transient multidimensional eccentric input for MUEF. The unbalanced electromagnetic force calculated by MUEF is fed back to VDMAD as excitation. The actual load torque output by the motor control model is fed back to itself to simulate the actual road load, thereby realizing the transient solution of electromechanical coupling.

[0015] Furthermore, the dynamic response of the VDMAD includes stator / rotor vertical displacement and axial deflection angle.

[0016] Compared with the prior art, the present invention has the following advantages: This invention constructs a six-degree-of-freedom vertical dynamic model (VDMAD) considering the axial deflection of the stator and rotor, a multidimensional eccentric unbalanced electromagnetic force model (MUEF), and a motor control model. Then, it performs transient electromechanical coupling on the VDMAD, MUEF, and motor control models to establish a multidimensional eccentric electromechanical coupling model (MDEEC). The vehicle axle load and road surface roughness are input as external excitations to the MDEEC. By solving the dynamic equations in a closed loop, the transient multidimensional eccentricity, unbalanced electromagnetic force, and vibration characteristics of the external rotor hub motor can be obtained. This accurately characterizes the axial structural features and transient multidimensional eccentricity coupling effect of the external rotor hub motor, precisely solves the dynamic characteristics of the external rotor hub motor under coupled excitation, and improves the model's prediction accuracy.

[0017] This invention introduces the axial deflection degree of freedom of the stator and rotor into the dynamic model of an external rotor hub motor for the first time, and constructs a six-degree-of-freedom vertical dynamic model VDMAD. By combining the axial distribution of axial angular stiffness, center of mass position and load position, it realizes the coupled characterization of radial eccentricity and axial eccentricity, solves the problem of oversimplification of axial structure in traditional models, and can more accurately reflect the actual structural characteristics of the external rotor hub motor.

[0018] The MUEF model proposed in this invention decomposes transient multidimensional eccentricity into radial and axial components, both of which include static and dynamic components. It combines eccentricity correction coefficients and Maxwell stress tensors to calculate unbalanced electromagnetic forces, taking into account the static eccentricity effect of the vehicle axle load. This avoids the defect of traditional models that treat eccentricity as a constant and can accurately calculate transient higher-order unbalanced electromagnetic force components.

[0019] The MDEEC model established in this invention realizes the closed-loop transient electromechanical coupling of VDMAD, MUEF and motor control model. It comprehensively considers the coupling excitation effect of vehicle axle load, road surface roughness and unbalanced electromagnetic force, improves the prediction accuracy of the model, and can accurately solve the transient multidimensional eccentricity and vibration characteristics of the external rotor hub motor.

[0020] The modeling method of this invention achieves accurate calculation of transient multidimensional eccentricity through state-space method and numerical solution. It can clarify the influence of axial deflection degree of freedom, vehicle axle load, and unbalanced electromagnetic force on the dynamic characteristics of external rotor hub motor. It provides clear theoretical guidance for hub bearing stiffness design, load-bearing structure optimization, and unbalanced electromagnetic force harmonic suppression of external rotor hub motor, which helps to improve the NVH characteristics and reliability of external rotor hub motor. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a schematic diagram of the internal structure of an external rotor permanent magnet synchronous motor. Figure 3A schematic diagram of the structure of the six-degree-of-freedom vertical dynamics model VDMAD; Figure 4 This is a schematic diagram of the geometric features of radial and axial eccentricity in an external rotor hub motor. Figure 5 A schematic diagram illustrating the decomposition of unbalanced electromagnetic forces; Figure 6 This is a schematic diagram of the principle of the multidimensional eccentric electromechanical coupling model MDEEC. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0023] Example like Figure 1 As shown, a multidimensional electromechanical coupling dynamics modeling and analysis method for an external rotor hub motor includes: A six-degree-of-freedom vertical dynamic model VDMAD considering the axial deflection of the stator and rotor is constructed, and a multidimensional eccentric unbalanced electromagnetic force model MUEF is constructed. A motor control model is constructed to provide electromagnetic force calculation input for MUEF and speed input for road roughness excitation for VDMAD; Transient electromechanical coupling was performed on VDMAD, MUEF, and the motor control model to establish a multidimensional eccentric electromechanical coupling model MDEEC. The vehicle axle load and road surface roughness were used as external excitation inputs to MDEEC. The transient multidimensional eccentricity, unbalanced electromagnetic force, and vibration characteristics of the outer rotor hub motor were obtained by solving the dynamic equation in a closed loop.

[0024] Specifically, the process of building a VDMAD includes: Considering the axial structural characteristics of an external rotor hub motor, a six-degree-of-freedom vertical dynamic model (VDMAD) is constructed, encompassing the vertical directions of 1 / 4 sprung mass, stator vertical direction + axial deflection, rotor vertical direction + axial deflection, and tire vertical direction. This model incorporates the axial angular stiffness and damping coefficients of the suspension, hub bearings, and tires, clearly defining the centroid positions of the stator and rotor, as well as the axial coordinates of the load-bearing positions of the suspension, hub bearings, seals, and wheel rims. Through fixture loading tests, the radial and angular stiffness of the hub bearings are identified. The VDMAD dynamic equations are established using d'Alembert's principle, with the vehicle axle load and road surface roughness as external excitations, enabling preliminary calculations of transient multidimensional eccentricity.

[0025] Among them, road surface roughness is modeled by white noise filtering method, and transient multidimensional eccentricity is divided into static component generated by vehicle axle load and dynamic component generated by road surface and electromagnetic force coupling excitation. Static component is solved by zeroing dynamic excitation, and dynamic component is solved numerically by state space method.

[0026] The process of building MUEF includes: The transient multidimensional eccentricity of the external rotor hub motor is decomposed into transient radial eccentricity and axial eccentricity, both of which contain static and dynamic components. Radial eccentricity correction coefficients are established based on the stator-rotor center offset, and axial eccentricity correction coefficients are established based on the stator-rotor axial deflection angle. The relative permeability of the air gap is corrected using these correction coefficients. The radial and tangential electromagnetic forces in the air gap are calculated based on Maxwell stress tensor, combining the permanent magnet flux density, armature flux density, and the complex relative permeability of the air gap in the stator slot. The circumferentially distributed electromagnetic forces are integrated along the axial direction and decomposed into unbalanced vertical forces and axial deflection torques acting on the VDMAD, thus completing the construction of the MUEF.

[0027] The process of constructing a motor control model includes: Based on the traditional permanent magnet synchronous motor control strategy, a motor control model for an external rotor hub motor is constructed. The target torque and target speed are input, and the feedback of transient load torque is considered. The output is three-phase current, motor angle and actual speed consistent with the actual working conditions. Among them, the three-phase current and motor angle provide input parameters for electromagnetic force calculation of MUEF, and the actual speed provides input parameters for road roughness excitation modeling of VDMAD.

[0028] The process of establishing MDEEC includes: A multidimensional eccentric electromechanical coupling model (MDEEC) is established by transiently coupling VDMAD, MUEF, and the motor control model. This model is a closed-loop feedback system: the dynamic response of VDMAD (stator / rotor vertical displacement, axial deflection angle) provides transient multidimensional eccentric input to MUEF; the unbalanced vertical force and axial deflection torque calculated by MUEF are fed back to VDMAD as electromagnetic excitation; and the actual load torque output by the motor control model is fed back to itself to simulate actual road load. The vehicle axle load and road surface roughness are used as external excitation inputs to MDEEC. By solving the dynamic equations, the transient multidimensional eccentricity, unbalanced electromagnetic force, and vibration characteristics of the external rotor hub motor are obtained.

[0029] This embodiment applies the above scheme, taking a surface-mount external rotor permanent magnet synchronous external rotor hub motor as the research object (the internal structure of the motor is as follows). Figure 2 As shown in the figure, the modeling process is as follows: 1. Construct a six-degree-of-freedom vertical dynamic model, VDMAD (e.g., Figure 3 (As shown) 1.1 Model parameter definition: , , and These are the vertical displacements of 1 / 4 of the sprung load, stator, rotor, and tire. , These are the axial deflection angles of the stator and rotor, respectively. , , and These are 1 / 4 of the sprung mass, stator mass, rotor mass, and tire mass. , , , and These are the vertical stiffness of the suspension, seals, wheel bearings, rims, and tires. , , and This is the corresponding damping. , ,and These are the angular stiffness of the suspension, wheel bearings, and tires. , and This is the corresponding damping. It is the axial length of the air gap. , and These are the distances between the stator center of gravity and the suspension bearing point, and between the wheel hub bearing bearing point and the seal bearing point, respectively. , and These represent the distances between the rotor's center of mass and the bearing points of the hub, seal, and rim, respectively.

[0030] 1.2 Establishment of Dynamic Equations: Based on d'Alembert's principle, dynamic equations were established for the 1 / 4 sprung mass, stator, rotor, and tire respectively, and then integrated into a set of dynamic equations: (1) 1.3 Road surface roughness modeling: White noise filtering method is used to model the vertical displacement of the road surface. The expression is shown in equation (2): (2) The lower cutoff frequency =0.011m -1 Reference space frequency =0.1m -1 B-grade road surface roughness coefficient =64×10 -6 m 3 vehicle speed White noise .

[0031] 1.4 Integrate the equations in 1.2 and 1.3 into matrix form: ,in For displacement vectors, , and Let F be the mass, damping, and stiffness matrices, respectively, and F be the external excitation vector. When only considering the road surface excitation input, F is... .

[0032] 1.5 Transient Multidimensional Eccentricity Solution: The axle load of the entire vehicle... As the input vector for VDMAD, the static radial eccentricity is obtained by solving. Static axial eccentricity Using the road surface excitation as the VDMAD input vector, the dynamic response is numerically solved using the state-space method to obtain the dynamic radial eccentricity. and dynamic axial eccentricity Then transient radial eccentricity Transient axial eccentricity .in, , , and We obtain the following from equation (3): (3) 2. Constructing a multidimensional eccentric unbalanced electromagnetic force model MUEF 2.1 Establishment of eccentricity correction coefficient: Radial eccentricity correction factor ,in This is the normal air gap length. It is an inscribed angle; Axial eccentricity correction factor ,in This refers to the axial position.

[0033] Figure 4 The schematic diagrams of radial and axial eccentricity shown illustrate the geometric features of radial and axial eccentricity of the external rotor hub motor, and mark key parameters such as stator-rotor center offset, axial deflection angle, and initial air gap length.

[0034] 2.2 Calculation of air gap magnetic flux density: using and Correcting the relative permeability of the air gap, combined with the radial / tangential magnetic flux density of the permanent magnet. , Armature radial / tangential magnetic flux density , The corrected air gap radial magnetic flux density is calculated using equation (4). and tangential magnetic flux density : (4) 2.3 Electromagnetic force calculation: The radial and tangential electromagnetic force densities were calculated based on Maxwell's stress tensor method (Equation (5)). and , (5) In the formula, Let be the vacuum permeability. Then, the electromagnetic force density is integrated along the vertical direction of the entire vehicle and decomposed into an unbalanced vertical force. and axial deflection torque As shown in equation (6).

[0035] (6) Figure 5 The process and location of action of decomposing the circumferentially distributed electromagnetic force into an unbalanced vertical force and an axial deflection torque after integration along the axial direction are shown.

[0036] After electromechanical coupling, an electromagnetic excitation input vector is added to the dynamic model: (7) At this point, the final MDEEC dynamic equations are formed: (8) 3. Construction of the motor control model for the external rotor hub motor Based on the rotor field-oriented motor control strategy of permanent magnet synchronous motor, a motor control model is constructed, and the target torque is input. Target speed Considering transient load torque The feedback is adjusted through the current loop and speed loop to output three-phase current. , , Motor rotation angle and actual speed ;in, , , and Enter MUEF, Enter VDMAD and convert it to u Used for road surface excitation modeling.

[0037] 4. Establishment of the Multidimensional Eccentric Electromechanical Coupling Model (MDEEC) The VDMAD, MUEF, and motor control model are coupled in a closed-loop transient manner. The coupling process of MDEEC is as follows: 4.1 Input target torque and target speed The motor control model outputs three-phase current, motor rotation angle, and actual speed. 4.2 The actual rotational speed is input into VDMAD, and the road surface excitation is obtained by combining it with the road surface roughness model. At the same time, the axle load of the whole vehicle is input, and VDMAD solves for the stator / rotor vertical displacement and axial deflection angle, that is, the transient multidimensional eccentricity. and ; 4.3 Input the transient multidimensional eccentricity, three-phase current, and motor rotation angle into MUEF to solve for the unbalanced vertical force. and axial deflection torque And as an electromagnetic excitation, it is fed back to the VDMAD; 4.4 VDMAD combines the vehicle axle load, road surface excitation and electromagnetic excitation to resolve the dynamic response and form a closed loop; at the same time, the actual load torque TL obtained from the motor control model is fed back to itself to simulate the actual road load. like Figure 6 As shown, MDEEC consists of the VDMAD model, the MUEF model, and the motor control model. Figure 6 The inputs, outputs, and closed-loop feedback links of each model are shown, clearly reflecting the core steps of electromechanical coupling.

[0038] 4.5 By numerically solving the dynamic equations of MDEEC, the system states of the external rotor hub motor, such as transient multidimensional eccentricity, unbalanced electromagnetic force, and stator vibration acceleration, are obtained.

[0039] In summary, this proposed solution fully considers the axial structural characteristics and transient multidimensional eccentric coupling effect of the external rotor hub motor, enabling accurate solution of the dynamic characteristics of the external rotor hub motor under coupled excitation, with high model prediction accuracy. The proposed solution can be simulated and solved using computer programs, making it suitable for the structural design, parameter optimization, and NVH suppression of external rotor hub motors. It can be widely applied in the research and development and production of external rotor hub motors for electric vehicles, demonstrating significant industrial practicality and promotional value.

Claims

1. A method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor, characterized in that, include: A six-degree-of-freedom vertical dynamic model VDMAD considering the axial deflection of the stator and rotor is constructed, and a multidimensional eccentric unbalanced electromagnetic force model MUEF is constructed. A motor control model is constructed to provide electromagnetic force calculation input for MUEF and speed input for road roughness excitation for VDMAD; Transient electromechanical coupling was performed on VDMAD, MUEF, and the motor control model to establish a multidimensional eccentric electromechanical coupling model MDEEC. The vehicle axle load and road surface roughness were used as external excitation inputs to MDEEC. The transient multidimensional eccentricity, unbalanced electromagnetic force, and vibration characteristics of the outer rotor hub motor were obtained by solving the dynamic equation in a closed loop.

2. The method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor according to claim 1, characterized in that, The process of constructing the six-degree-of-freedom vertical dynamic model VDMAD, which considers the axial deflection of the stator and rotor, includes: Considering the axial structural characteristics of the external rotor hub motor, a six-degree-of-freedom vertical dynamic model (VDMAD) is constructed, including 1 / 4 of the sprung mass vertical degree of freedom, stator vertical and axial deflection degrees of freedom, rotor vertical and axial deflection degrees of freedom, and tire vertical degree of freedom. This model introduces the axial angular stiffness and damping coefficient of the suspension, hub bearing, and tire, clarifies the centroid positions of the stator and rotor, and the axial coordinates of the load-bearing positions of the suspension, hub bearing, seals, and rim. The radial stiffness and angular stiffness of the hub bearing are identified through a fixture loading test. The VDMAD dynamic equation is established by combining the d'Alembert principle. The vehicle axle load and road surface roughness are used as external excitations to calculate transient multidimensional eccentricity.

3. The method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor according to claim 2, characterized in that, The transient multidimensional eccentricity includes a static component generated by the vehicle axle load, and a dynamic component generated by the coupling excitation of road surface roughness and unbalanced electromagnetic force.

4. The method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor according to claim 3, characterized in that, The process of calculating transient multidimensional eccentricity includes: The static components are obtained by solving the VDMAD dynamic equations with the dynamic excitation set to zero. The dynamic components are obtained by numerically solving the dynamic response of VDMAD using the state-space method.

5. The method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor according to claim 3, characterized in that, The process of constructing the multidimensional eccentric unbalanced electromagnetic force model MUEF includes: The transient multidimensional eccentricity of the external rotor hub motor is decomposed into transient radial eccentricity and axial eccentricity, both of which contain static and dynamic components. The relative permeability of the air gap is corrected using radial eccentricity correction coefficients and axial eccentricity correction coefficients; The radial and tangential electromagnetic forces in the air gap are calculated based on the Maxwell stress tensor. The circumferentially distributed electromagnetic forces are integrated along the axial direction and decomposed into unbalanced vertical forces and axial deflection torques acting on the VDMAD, thus completing the construction of the MUEF.

6. The method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor according to claim 5, characterized in that, The radial eccentricity correction coefficient is specifically a function based on the stator and rotor center offset, the initial length of the air gap, and the circumferential angle; The axial eccentricity correction coefficient is specifically a function based on the axial deflection angle of the stator and rotor and the axial length of the air gap.

7. The method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor according to claim 5, characterized in that, The Maxwell stress tensor is specifically calculated by combining the magnetic flux density of the permanent magnet, the magnetic flux density of the armature, and the complex relative permeability of the air gap in the stator slot.

8. The method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor according to claim 1, characterized in that, The process of constructing the motor control model includes: Based on the rotor field-oriented motor control strategy of permanent magnet synchronous motor, a motor control model for external rotor hub motor is constructed. The target torque and target speed are input, and the feedback of transient load torque is considered. The output is three-phase current, motor angle and actual speed consistent with the actual working conditions. Among them, the three-phase current and motor angle provide input parameters for electromagnetic force calculation of MUEF, and the actual speed provides input parameters for road roughness excitation modeling of VDMAD.

9. The method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor according to claim 8, characterized in that, The process of transient electromechanical coupling of VDMAD, MUEF, and the motor control model includes: The dynamic response of VDMAD is used to provide transient multidimensional eccentric input for MUEF. The unbalanced electromagnetic force calculated by MUEF is fed back to VDMAD as excitation. The actual load torque output by the motor control model is fed back to itself to simulate the actual road load, thereby realizing the transient solution of electromechanical coupling.

10. The method for multidimensional electromechanical coupling dynamics modeling and analysis of an external rotor hub motor according to claim 9, characterized in that, The dynamic response of the VDMAD includes stator / rotor vertical displacement and axial deflection angle.

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