Solving method of electromagnetic design used for surface-mounted permanent magnet motor

Abstract

The invention discloses a solving method electromagnetic design used for a surface-mounted permanent magnet motor. The solving method comprises the following steps: (1) based on an improved subdomainmethod, establishing a vector magnetic potential expression of a permanent magnet, an air gap and a stator slot, and obtaining current magnetic field distribution of three subdomains according to thevector magnetic potential expression, wherein an equivalent current sheet is added into the stator slot as a boundary condition, the vector magnetic potential expression of the stator slot is relatedto the current density of the equivalent current sheet; (2) according to the obtained current magnetic field distribution, using a magnetic circuit method to solve and obtain the magnetic voltage dropof each part of a stator core, and converting the magnetic voltage drop into the current density of the equivalent current sheet inside the stator slot; (3) through mutual iteration of the improved subdomain method and the magnetic circuit method, solving the magnetic field distribution of the three subdomains; and (4) calculating permanent magnet motor magnetic flux linkage, counter electromotive force and cogging torque. By using the solving method, the magnetic field distribution of the motor and the electromagnetic performance of the motor under the condition that a saturation effect is considered can be calculated accurately, and optimal opinions are provided for motor design.

Description

technical field [0001] The invention belongs to the technical field of permanent magnet motors, and in particular relates to a solution method for electromagnetic design of surface-mounted permanent magnet motors. Background technique [0002] Permanent magnet motors have attracted extensive attention because of their high torque density, power density, and efficiency. In order to design and optimize a permanent magnet motor that meets the application requirements, and to shorten the design cycle as much as possible, it is very important to select an appropriate model for electromagnetic analysis at different design stages of the motor. For example, in the initial stage of motor design, designers often hope that the motor model can be solved quickly to quickly find the design direction; while in the later stage of motor design, designers hope that the motor model should be as accurate as possible, closer to the actual results, and reduce errors. [0003] Existing models can...

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Problems solved by technology

The numerical model can solve the motor with complex structure and accurately calculate the saturation effect of the iron core, but usually the solution time is too long, resulting in a long design cycle, and the performance cannot directly correspond to the size parameters of the motor, so performance optimization is difficult

The analytical method is fast to solve, and because the motor performance is directly related to the size parameters, it can provide optimization advice. It is usually divided into relative permeability method, complex permeability method and subdomain method. However, the analytical method can only solve the linear model. , that is, it is assumed that the stator and rotor cores of the motor have infinite magnetic permeability, so the error will increase with the increase of the saturation degree of the motor

The magnetic circuit method can also calculate the nonlinearity of the iron core through Kirchhoff's law and Newton-Raphson's method. However, there are a lot of simplification processes in the magnetic circuit equivalent, which essentially discretize a continuous field distribution, so The magnetic field distribution cannot be accurately predicted

[0004] Therefore, in order to combine the advantages of the analytical method and the magnetic circuit method, that is, the accuracy of magnetic field prediction and the calculation of nonlinearity, some composite models based on conformal transformation have been proposed, however, these models cannot accurately calculate the magnetic field distribution in the slot , will bring some errors to the calculation results.

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