Method for calculating heat transfer ratio based on eddy current loss of rotor segmented sheath of permanent magnet motor

Abstract

The embodiment of the invention provides a method for calculating a heat transfer ratio based on the eddy current loss of a rotor segmented sheath of a permanent magnet motor. The method comprises thefollowing steps: separately establishing a field circuit coupling calculation model with a segmented sheath and a field circuit coupling calculation model without sheath for the permanent magnet motor based on vector control, and calculating the loss of each component; then, separately establishing a three-dimensional steady state temperature field solution model with a segmented sheath and a three-dimensional steady state temperature field solution model without sheath for the permanent magnet motor, determining a boundary condition based on an assumed condition, and obtaining a rotor steadystate heat conduction equation; separately calculating a heat conductivity coefficient in an air gap and the heat conductivity coefficient of a stator winding, substituting the heat conductivity coefficients in the rotor steady state heat conduction equation, and using the loss as the heat source of a solution domain to obtain a steady state temperature field of the permanent magnet motor; and separately calculating the temperature of each component under the action on basic wave current on the permanent magnet motor in which the rotor has no sheath and the permanent magnet motor in which therotor has the segmented sheath, and calculating the heat transfer ratio of each component according to the temperature of each component. The method provided by the invention provides important theoretical basis for the design of an electromagnetic structure of the permanent magnet motor.

Description

technical field [0001] The invention relates to the technical field of permanent magnet motors, in particular to a method for calculating heat transfer ratio based on eddy current loss of a segmented sheath of a permanent magnet motor rotor. Background technique [0002] The permeance harmonics caused by the segmented sheath on the surface of the permanent magnet motor will not only increase the loss of the motor, but also increase the reactive power of the motor, which will significantly reduce the power factor of the motor. A large number of permeance harmonics will also overheat the motor windings and damage the insulation of the motor windings. Excessive temperature may cause the permanent magnets to lose their magnetism and shorten the service life of the motor. On this basis, it is necessary to analyze the heat transfer direction inside the motor, so as to propose the concept of heat conduction ratio, which has good engineering application value. [0003] The eddy cur...

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Problems solved by technology

[0003] The eddy current loss caused by the segmented sheath on the surface of the permanent magnet motor may generate harsh electromagnetic noise in the motor. At the same time, it may also cause problems such as motor torque ripple and electromagnetic interference. The loss is relatively large, and it is easy to cause high temperature of the permanent magnet, and the permanent magnet is affected by the high temperature, which will reduce its excitation performance, and may also cause irreversible loss of magnetism of the permanent magnet, which will affect the service life of the motor and reduce the working efficiency of the entire motor

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