Analysis of the Asynchronous Electrical Motor Length Effect on the Magnetic Field Distribution and on the Force Torque Created by This Field

Authors: Persova M. G., Soloveychik Yu. G., Gamadin M. V., Serdobintseva M. L.

Annotation: This article is devoted to the finite element schemes of 3D modeling of electromagnetic fields in asynchronous motors. These calculation schemes are based on the joint use of quasi 3D and 3D formulations. The quasi 3D formulation is used for modeling the electrodynamic process in a motor and includes the calculation of the electromagnetic field in the cross-section of the motor. This electromagnetic field calculation is used for evaluation of the stator and the rotor currents with their closure at the end zones of a motor taking into account. The 3D formulation is based on solving a 3D nonlinear task of magnetostatics in which the currents in stator and rotor windings are calculated in the quasi 3D formulation and used as sources. The mathematical apparatus for solving a 3D problem and the method of calculating the electromagnetic force in the volume of an electrical machine are described in the article. The results concerning the calculation of the volume and surface components of the electromagnetic force torque and their sum for different space discretizations are given. It shows the accuracy of the results obtained. The comparison of the force torque calculated using the distribution of magnetic induction and the force torque calculated using through the balance of powers is given. The values of the torques produced by the electromagnetic force in separate sections of the electric machine are analyzed. The effects of the length of an asynchronous electrical motor on the magnetic field distribution and on the force torque created by this field are evaluated. It is shown that the influence of the end zones of the motor structure on the value of magnetic fluxes and the value of the force torque when designing an electric machine is insignificant, even if the length of this electric machine is half its diameter.

Keywords: 3d modelling, electromagnetic field, finite element method, asynchronous electrical motor, quasi 3d formulation, nonlinear tasks, force torque, total scalar potential method, non-total scalar potential method