Method for analyzing sealing performance of motor controller of new energy automobile

Abstract

The invention discloses a new energy automobile motor controller sealing performance analysis method. The method comprises the steps that S1, a motor controller sealing assembly three-dimensional model comprises a wiring cover plate, an upper cover plate, a box body, a lower cover plate and bolts; s2, extracting a center line of a sealing surface according to the width of an assembly groove of the sealant or the sealing ring, and dividing the sealing upper surface and the sealing lower surface by using the center line; s3, performing finite element mesh modeling on the processed model; s4, the motor controller box fastening bolt flange face is in frictional contact with the wiring cover plate, the upper cover plate and the lower cover plate; s5, endowing each part with a material attribute; s6, sealant or sealing ring resilience force is applied to center line unit nodes of the upper sealing surface and the lower sealing surface, pre-tightening force is applied to bolts, airtight pressure is applied to an inner cavity of the controller, and the positions of installation points of the controller are fully restrained; and S7, carrying out solution calculation on the established finite element model by adopting a solver. According to the invention, the sealing performance of the motor controller can be rapidly evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicle motor controllers, and in particular to a method for analyzing the sealing performance of new energy vehicle motor controllers. Background Art

[0002] The motor control unit (MCU) is a core power electronic unit unique to new energy vehicles. It mainly receives driving control instructions from the vehicle controller VCU, controls the drive motor to output the specified torque and speed, realizes the conversion of the DC power of the power battery into the required high-voltage AC power, and drives the motor body to output mechanical energy, thereby ensuring the normal driving of the vehicle. The MCU is mainly composed of a structural housing, a power electronic unit, a control circuit, underlying software, and control algorithm software. It has the functions of motor system fault diagnosis, protection, and storage, and has an important impact on the power, economy, reliability, and safety of the vehicle.

[0003] One of the key factors for the normal operation of the motor controller is its good sealing, which determines the safety of the entire vehicle. If there is a risk of the controller's sealing, it may cause the controller to short-circuit and cause a "machine explosion" phenomenon in serious cases. Each motor controller will be tested for airtightness at the end of the production line when it is off the line to ensure that there will be no sealing failure in actual work, ensuring the normal operation of the controller and the normal driving of the vehicle.

[0004] Therefore, in order to ensure the sealing of the controller in the early stage of design, how to establish a simulation analysis method for the sealing of the controller is particularly critical for quickly, efficiently and accurately evaluating its sealing performance. Summary of the invention

[0005] The present invention provides a method for analyzing the sealing performance of a motor controller of a new energy vehicle. The present invention can quickly evaluate the sealing performance of the motor controller.

[0006] The technical solutions to the above problems are as follows:

[0007] A method for analyzing the sealing performance of a motor controller of a new energy vehicle comprises the following steps:

[0008] S1, preparing a three-dimensional model of a motor controller sealing assembly, the three-dimensional model of the motor controller sealing assembly including a wiring cover plate, an upper cover plate, a box body, a lower cover plate, and bolts;

[0009] S2, model processing, extracting the center line of the sealing surface according to the width of the assembly groove of the sealant or the sealing ring, and using the center line to divide the upper and lower surfaces of the seal respectively;

[0010] S3, performing finite element mesh modeling on the processed model, and making the number of nodes on the sealing center line equal and one-to-one corresponding during modeling;

[0011] S4, creating contact pairs, the flange surfaces of the fastening bolts of the motor controller housing respectively establish frictional contact with the wiring cover, the upper cover, and the lower cover, and the threaded part of the bolts establishes binding contact with the housing;

[0012] S5, assign material properties to each component, including the elastic model, Poisson's ratio and density of the upper cover, box, lower cover and bolts;

[0013] S6, apply loads, apply the sealant or seal ring rebound force on the midline unit nodes of the upper and lower surfaces of the seal, apply pre-tightening force to the bolts, and apply airtight pressure to the inner cavity of the controller. The controller installation point position is fully constrained;

[0014] S7, using a solver to solve and calculate the established finite element model, and evaluating whether the motor controller meets the sealing requirements based on the calculation results.

[0015] The present invention can perform finite element numerical simulation analysis on the sealing performance of the sealing component of the new energy motor controller. Through this method, the deformation curve of the sealing surface can be obtained, and the performance of the electric control sealing can be intuitively understood, so as to strengthen the risk area of ​​sealing failure and perform weight reduction design on the over-strengthened area, thereby providing directional guidance and theoretical basis for the initial design and subsequent improvement of the controller housing and component sealing.

[0016] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Flow chart for implementing the present invention.

[0018] Figure 2 It is a schematic diagram of the centerline structure of the sealing surface divided by the upper cover plate and the lower cover plate.

[0019] Figure 3 This is the sealing simulation analysis result. DETAILED DESCRIPTION

[0020] like Figures 1 to 3 As shown, a method for analyzing the sealing performance of a motor controller for a new energy vehicle of the present invention comprises the following steps:

[0021] S1, prepare a three-dimensional model of the motor controller sealing component, the three-dimensional model of the motor controller sealing component includes a wiring cover, an upper cover, a box body, a lower cover and bolts; in the present invention, the three-dimensional model of the motor controller sealing component is imported into the three-dimensional modeling UG software, the center line of the sealing surface is extracted, and the sealing surface is segmented.

[0022] S2, model processing, import the processed 3D model into HyperMesh software, that is, the 3D model of the wiring cover, upper cover, box, lower cover and bolts, extract the sealing surface centerline 1 according to the assembly groove width of the sealant or sealing ring, and use the centerline 1 to divide the upper and lower surfaces of the seal respectively.

[0023] S3, mesh discretization is performed, and finite element mesh modeling is performed on the processed model. When modeling, the number of nodes on the seal centerline is equal and one-to-one corresponding. To improve the calculation accuracy, the bolts use first-order hexahedral elements, and the other parts use ten-node tetrahedral elements.

[0024] S4, create contact pairs, the flange surfaces of the fastening bolts of the motor controller box establish friction contacts with the wiring cover, upper cover, and lower cover respectively, and the threaded part of the bolt establishes binding contact with the box.

[0025] S5, assign material properties to each component, including the elastic model (MPa), Poisson's ratio and density (Kg / m^3) of the upper cover, box, lower cover and bolts.

[0026] S6, apply load, apply sealant or sealing ring rebound force (same size, opposite direction) on the midline unit nodes of the upper and lower surfaces of the seal, apply pre-tightening force on the bolts, and apply airtight pressure on the inner cavity of the controller. The controller installation point position is fully constrained.

[0027] S7, use OptiSturct solver to solve and calculate the established finite element model, and evaluate whether the motor controller meets the sealing requirements based on the calculation results. OptiSturct is a solver under the finite element software Hyperworks (enterprise-level CAE platform). After the processed model is submitted to this solver for calculation, a result file will be output after the calculation is completed, and the result file can be processed.

[0028] According to Newton's method for nonlinear solution, we first obtain the tangent stiffness of the starting point by differentiation, and then solve the linear equation to obtain a trial solution and check the residual. If the convergence criterion is not met, the starting point is updated and the tangent stiffness matrix is ​​solved again until the convergence criterion is met to obtain the solution to the equation.

[0029] In step S7, the solution is calculated as follows:

[0030] The structural equilibrium equation is expressed as:

[0031] L(u)=P (1)

[0032] In formula (1), u is the displacement vector, P is the global load vector, and L(u) is the system response;

[0033] L(u) can be further expressed as:

[0034] Ku=P (2)

[0035] In formula (2), K is the system stiffness;

[0036] For formula (1), the iterative process is as follows:

[0037] K n .Δu n =R n (3)

[0038] u n+1 =u n +Δu n (4)

[0039] in:

[0040]

[0041] R n =PL(u n ) (6)

[0042] In the above formula, Δu n represents the displacement increment of the nth iteration, u n represents the displacement of the nth iteration, u n+1 represents the displacement of n+1 iterations, represents the derivative of the system response, represents the derivative of displacement, K n represents the tangent stiffness matrix at the nth iteration, R n Represents the residual after the nth iteration;

[0043] The solution operation repeats the above process until the residual meets the convergence criterion;

[0044] The displacement convergence criterion can be expressed as:

[0045]

[0046] ||Au||=∑ i |A i u i | (8)

[0047]

[0048] In the above formula, E u is the equivalent displacement error; q is the shrinkage factor, which is used to correct Δu and can better calculate the true error in nonlinear solutions; Δu is the displacement increment;

[0049] A is the normalized vector, ∑ i |Ai u i | represents the sum of total i displacements;

[0050] in, represents the square root of the diagonal elements of the i-th stiffness matrix K. The mode of the vector can be calculated by equation (8); u i represents the i-th displacement. In order to make q more stable in actual calculation, each iteration step is updated by formula (10):

[0051]

[0052] The initial value of the shrinkage factor is q1 = 0.99;

[0053] The force convergence criterion can be expressed as:

[0054]

[0055] In formula (10-11), q n represents the shrinkage factor for n iterations, q n-1 represents the shrinkage factor for n-1 iterations, Δu n represents the displacement increment of n iterations, Δu n-1 represents the displacement increment of n-1 iterations, E P is the equivalent force error; the load vector P is the external load. When the external load is a forced displacement, P is the equivalent node reaction force, and R represents the residual;

[0056] The energy convergence criterion can be expressed as:

[0057]

[0058] (12) In the formula, E w is the equivalent work error, other parameters are the same as above.

[0059] In step S7, according to the sealing performance design requirements, the maximum allowable deformation of the sealing surface is evaluated in the following manner:

[0060] ΔD<(δ1-δ0)×D0 (13)

[0061] In formula (13), ΔD is the maximum allowable deformation of the sealing surface; δ1 is the minimum compression of the sealant or sealing ring; δ0 is the compression to ensure the sealing performance; and D0 is the original thickness of the sealant or sealing ring.

[0062] Deformation: The sealing surface of the motor controller will deform under the action of the sealant or sealing ring rebound force, bolt preload and airtight pressure. The smaller the deformation, the better the sealing.

[0063] According to the simulation results in S6 and the evaluation criteria in S7, it is determined whether the sealing of the motor controller meets the requirements. If it does not meet the requirements, the sealing failure area is optimized and S1 to S7 are repeated until the sealing surface of the motor controller meets the sealing requirements.

[0064] In summary, the present invention provides a method for analyzing the sealing performance of a motor controller, the boundary conditions of which are consistent with reality, and the results can reflect the real situation. Through this method, the sealing performance of the sealing surface of the motor controller can be intuitively, accurately and quickly understood, thereby guiding the structural optimization design and rationally arranging the bolts.

[0065] The above-mentioned embodiments are some embodiments of the present invention, but not all embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and cannot be simply understood as limiting the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

Claims

1. A method for analyzing the sealing performance of a motor controller of a new energy vehicle, characterized in that: The following steps are involved: S1, preparing a three-dimensional model of a motor controller sealing assembly, the three-dimensional model of the motor controller sealing assembly including a wiring cover plate, an upper cover plate, a box body, a lower cover plate, and bolts; S2, model processing, extracting the center line of the sealing surface according to the width of the assembly groove of the sealant or the sealing ring, and using the center line to divide the upper and lower surfaces of the seal respectively; S3, performing finite element mesh modeling on the processed model, and making the number of nodes on the sealing center line equal and one-to-one corresponding during modeling; S4, creating contact pairs, the flange surfaces of the fastening bolts of the motor controller housing respectively establish frictional contact with the wiring cover, the upper cover, and the lower cover, and the threaded part of the bolts establishes binding contact with the housing; S5, assign material properties to each component, including the elastic model, Poisson's ratio and density of the upper cover, box, lower cover and bolts; S6, apply loads, apply the sealant or seal ring rebound force on the midline unit nodes of the upper and lower surfaces of the seal, apply pre-tightening force to the bolts, and apply airtight pressure to the inner cavity of the controller. The controller installation point position is fully constrained; S7, using a solver to solve and calculate the established finite element model, and evaluating whether the motor controller meets the sealing requirements based on the calculation results.

2. The method for analyzing the sealing performance of a motor controller for a new energy vehicle according to claim 1, characterized in that: In step S7, the solution is calculated as follows: The structural equilibrium equation is expressed as: L(u)=P (1) In formula (1), u is the displacement vector, P is the global load vector, and L(u) is the system response; L(u) can be further expressed as: Ku=P (2) In formula (2), K is the system stiffness; For formula (1), the iterative process is as follows: K n .Δu n =R n (3) u n+1 =u n +Δu n (4) in: R n =P-L(u n ) (6) In the above formula, Δu n represents the displacement increment of the nth iteration, u n represents the displacement of the nth iteration, u n+1 represents the displacement of n+1 iterations, represents the derivative of the system response, represents the derivative of displacement, K n represents the tangent stiffness matrix at the nth iteration, R n Represents the residual after the nth iteration; The solution operation repeats the above process until the residual meets the convergence criterion; The displacement convergence criterion can be expressed as: ||A.u||=∑ i |A i u i | (8) In the above formula, E u is the equivalent displacement error; q is the shrinkage factor, which is used to correct Δu and can better calculate the true error in nonlinear solutions; Δu is the displacement increment; A is the normalized vector, ∑ i |A i u i | represents the sum of total i displacements; in, represents the square root of the diagonal elements of the i-th stiffness matrix K. The mode of the vector can be calculated by equation (8); u i represents the i-th displacement. In order to make q more stable in actual calculation, each iteration step is updated by formula (10): The initial value of the shrinkage factor is q1 = 0.99; The force convergence criterion can be expressed as: In formula (10-11), q n represents the shrinkage factor for n iterations, q n-1 represents the shrinkage factor for n-1 iterations, Δu n represents the displacement increment of n iterations, Δu n-1 represents the displacement increment of n-1 iterations, E P is the equivalent force error; the load vector P is the external load. When the external load is a forced displacement, P is the equivalent node reaction force, and R represents the residual; The energy convergence criterion can be expressed as: (12) In the formula, E w is the equivalent work error, other parameters are the same as above.

3. The method for analyzing the sealing performance of a motor controller for a new energy vehicle according to claim 1, characterized in that: In step S7, according to the sealing performance design requirements, the maximum allowable deformation of the sealing surface is evaluated in the following manner: ΔD<(δ1-δ0)×D0 (13) In formula (13), ΔD is the maximum allowable deformation of the sealing surface; δ1 is the minimum compression of the sealant or sealing ring; δ0 is the compression to ensure the sealing performance; and D0 is the original thickness of the sealant or sealing ring.

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