CN-121997668-A - High-precision magnetic network modeling method for heterogeneous grid self-adaption of permanent magnet synchronous motor

Abstract

The invention discloses a high-precision magnetic network modeling method for heterogeneous grid self-adaption of a permanent magnet synchronous motor, and belongs to the technical field of electromagnetic analysis of permanent magnet synchronous motors. According to the method, symmetrical sector grid division is performed by extracting single-slot or single-pole minimum period units of a motor structure, a polar coordinate function is utilized to accurately represent heterogeneous material boundaries, the magnetic permeability is calculated based on a geometric overlap principle, a unified matrix modeling fusion permanent magnet and stator winding magnetomotive force is adopted, and the stability of nonlinear solution is improved by combining a Newton Lafson iterative algorithm. The method simplifies the modeling flow, greatly reduces the preprocessing time and the computing time compared with the finite element method, and obviously improves the efficiency of multi-working-condition iterative optimization on the premise of ensuring high precision.

Inventors

• SUN QINGGUO
• LI MENGHAN

Assignees

• 河北工业大学

Dates

Publication Date

20260508

Application Date

20260129

Claims (5)

1. 1. The modeling method of the heterogeneous grid self-adaptive high-precision magnetic network of the permanent magnet synchronous motor is characterized by comprising the following steps of: Determining a minimum period unit of a stator and a minimum period unit of a rotor, and dividing the minimum period units by a sector grid structure to form a structured grid, wherein each sector grid unit is equivalent to two vertical magnetic permeabilities, which are defined as tangential magnetic permeabilities G t and radial magnetic permeabilities G r ; Firstly, inputting basic position information of a minimum period unit of a research object, constructing geometric boundary mathematical description under polar coordinates, defining a sector grid traversed by a heterogeneous contour of the minimum period unit as a heterogeneous grid, and forming uniform grids by the rest grids, wherein all the heterogeneous grids form the heterogeneous material region; The radial magnetic conductance and the tangential magnetic conductance of the silicon steel material and the non-silicon steel material are respectively calculated in each heterogeneous grid, and then the radial magnetic conductance and the tangential magnetic conductance of the whole fan-shaped grid unit are calculated; Comparing the relative sizes of radial magnetic conductance and tangential magnetic conductance of silicon steel materials in heterogeneous grids and radial magnetic conductance and tangential magnetic conductance of an air domain, automatically completing grid optimization and partitioning according to the principle of 'merging small magnetic conductance materials and retaining large magnetic conductance materials', and establishing a unit model; Finally, the Matlab program automatically generates a global model through rotary copying based on the unit model, and applies periodic boundary conditions and Dirichlet boundary conditions to ensure the continuity and consistency of a physical field; and carrying out iterative solution by utilizing Newton Lafson based on the self-adaptive magnetic conductance calculation result.
2. 2. The method according to claim 1, wherein the principle of merging small magnetic permeability materials and reserving large magnetic permeability materials is specifically that one of silicon steel materials and air domain magnetic permeability which is relatively smaller is included in a sector grid area adjacent to the same material, and the other magnetic permeability which is relatively larger is reserved in an original heterogeneous grid, so that homogenization treatment of materials in the heterogeneous grid is realized.
3. 3. The method according to claim 2, characterized in that the permeabilities of adjacent identical materials are classified, in particular, in that the synthesized tangential permeance G Yt is a parallel configuration of two tangential permeabilities before synthesis, seen in tangential direction, and in that the synthesized radial permeance G Yr is a series configuration of two radial permeabilities before synthesis, seen in radial direction.
4. 4. The method according to claim 1, wherein the specific process of performing iterative solution by newton-raphson based on the adaptive flux guide calculation result is: Adopting Newton Lapherson method to make iterative solution, introducing variable Newton damping factor alpha k to self-adaptively regulate iterative step length, The change rule of alpha k is as follows: (15) Wherein alpha base is a basic step length, B s is inflection point magnetic density of a B-H curve of the silicon steel material, and B sat is an adjustment coefficient; In each iteration step k, the non-linear residual F (x k ) and jacobian matrix J (x k ) are evaluated to update the solution, and if an entry into the saturation region is detected, the variable damping factor a k is adaptively adjusted to ensure numerical stability, and the iteration continues until the solution meets the convergence criterion |x k+1 -x k | < epsilon, where epsilon is a user-defined tolerance.
5. 5. The method of claim 1, wherein after introducing a rotor skewed pole structure in the motor design, axially segmenting and applying a phase offset to simulate, the electromagnetic torque integral equation is: (18) Wherein m represents the number of oblique pole segments, phi m is the oblique pole angle of each axial section, K represents the number of oblique poles, B t,m and B r,m are tangential magnetic flux density and radial magnetic flux density under each oblique pole segment, the magnetic flux density is obtained by iterative solution of the obtained magnetic flux density by using an equivalent magnetic network method based on the self-adaptive magnetic flux density calculation result, B t,m (T) and B r,m (T) are functions of time T, R outer and R inner respectively represent the outer radius and the inner radius of a fan-shaped grid unit, theta represents the central angle of the fan-shaped grid unit, mu 0 is the magnetic permeability of vacuum, L d is the effective axial length, and T is electromagnetic torque.

Description

High-precision magnetic network modeling method for heterogeneous grid self-adaption of permanent magnet synchronous motor Technical Field The invention belongs to the technical field of electromagnetic analysis of permanent magnet synchronous motors, and particularly relates to a heterogeneous grid self-adaptive high-precision magnetic network modeling method of a permanent magnet synchronous motor, which combines modeling precision and efficiency and is suitable for electromagnetic performance prediction and multiplexing Kuang Diedai analysis scenes of the permanent magnet synchronous motor. Background The permanent magnet synchronous motor has become a core component of high-performance application scenes such as electric automobile driving, industrial servo systems, wind power generation and the like by virtue of comprehensive advantages such as high torque density, high running efficiency, low noise characteristic, long service life and the like. In these fields, the accurate calculation of the electromagnetic field inside the motor is a key basis for evaluating its efficiency, torque ripple, vibration noise and verifying the rationality of the design. Currently, the mainstream electromagnetic analysis method mainly comprises three types, namely an analysis method, a finite element analysis method and an equivalent magnetic network method. Each method has the applicable scene and characteristics, and a complete tool box for motor design and analysis is formed together. However, magnetic field analysis of permanent magnet synchronous motors (particularly built-in and other complex rotor topologies) presents a number of challenges. The geometrical asymmetry of the rotor structure presents significant difficulties for mathematical description of boundary conditions, limiting the direct application of classical analytical models. Although the finite element method is capable of simulating the multi-physical field coupling problem with high accuracy by fine grid division, it is very expensive to calculate. Especially in the initial design stage of multi-parameter and multi-working condition iterative optimization, the sensitivity to complex lamination structures and nonlinear material properties can lead to long calculation time, thereby remarkably prolonging the research and development period. The equivalent magnetic network method is to make the internal magnetic circuit of the motor equivalent to a topological network composed of magnetic conduction and magnetomotive force sources, and solve the magnetic flux distribution by establishing a node magnetic potential equation. The method has the advantages that dense grid subdivision is not needed like a finite element method, the calculation speed is higher, and nonlinear factors such as the magnetic saturation effect of the iron core, the complex magnetic leakage path and the dynamic process of the rotor can be considered more carefully than the traditional magnetic circuit analysis method. However, the accuracy of the finite element method is likely to be different from that of the equivalent magnetic network method, the change of the grid shape is mainly used at present, but the accurate calculation is still performed on the premise of dividing a finer grid, which obviously increases the solving time, and how to enable the accuracy of the finite element method to be achieved within a shorter time by the equivalent magnetic network is a technical problem to be solved urgently. Disclosure of Invention The invention aims to overcome the defects of the existing electromagnetic modeling method of a permanent magnet synchronous motor, provides a heterogeneous grid self-adaptive high-precision magnetic network modeling method of the permanent magnet synchronous motor, and specifically solves the following technical problems: 1. The modeling flow is simplified, the preprocessing workload is reduced, and the tedious operation of manual node definition is avoided; 2. the magnetic conductance calculation precision of the heterogeneous material area is improved, and grid refinement is not required; 3. the rotor oblique pole effect is effectively integrated, and the prediction precision of parameters such as torque, air gap flux density and the like is improved; 4. optimizing an iterative solving algorithm, enhancing the numerical stability of a magnetic saturation region, and avoiding solving divergence; 5. On the premise of ensuring the accuracy equivalent to that of a finite element analysis method, the calculation cost is obviously reduced, and the multi-working-condition iterative optimization requirement is adapted. In order to achieve the above purpose, the invention adopts the following technical scheme: A method for modeling a heterogeneous grid self-adaptive high-precision magnetic network of a permanent magnet synchronous motor, comprising the following steps: Determining a minimum period unit (single stator slot) of a stator and a minimum period unit (si