Temperature rise analytical method for predicting temperature of permanent magnet in permanent magnet synchronous motor

Abstract

The invention relates to a temperature rise analytical method for predicting temperature of a permanent magnet in a permanent magnet synchronous motor (PMSM), belonging to the application electrical engineering design field; the method is characterized in that: distributed heat source of a motor is analyzed by a filed-circuit compact coupling method, comprising eddy current loss in the permanent magnet, iron loss in an iron core and copper loss in armature; on the consideration of precision requirements, the coupling analysis of a magnetic field and a temperature filed can be realized by single-way coupling mode. A thermal model of the permanent magnet synchronous motor is built based on a mixing method of a novel equivalent heat network and a finite element, heat parameters are rationally selected by adopting a combining mode of experimental measurement and empirical formula, the heat transferring coefficient and cooling condition of the motor are described completely, a stator and a rotor can be systematically combined by adopting air gap joints in the heat network, the stator and rotor unified temperature rise model is formed, the difficulty of measuring air gap temperature is avoided, material parameters are adopted at the practical working temperature, so as to lead the analysis to be rational; the accurate and optical method for predicting the temperature of the permanent magnet is realized by special correction processing in experimental links; in addition, the design method is used to give suggestions for model selection of the permanent magnet material in the motor.

Description

technical field [0001] The invention belongs to the field of applied electric technology, in particular to the temperature rise prediction analysis of a permanent magnet synchronous motor (PMSM). Background technique [0002] Permanent magnet synchronous motor (PMSM) has the characteristics of energy saving, high efficiency and simple structure. Specifically, permanent magnet synchronous motor does not need DC excitation power supply and attached contact devices such as brushes and slip rings, which can reduce mechanical and electrical losses and have high power factor. , Large starting torque, etc. In order to design high-efficiency motors, the temperature rise prediction of permanent magnets in permanent magnet synchronous motors is essential, especially due to the poor cooling conditions of the rotor, the eddy current loss of permanent magnets may cause high temperature rise, which in turn leads to loss of magnetism of permanent magnets. Reduced motor performance. The m...

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Problems solved by technology

NdFeB is the most widely used permanent magnet material. Compared with ferrite, although it has higher coercive force and remanence, it has higher electrical conductivity and poor heat resistance. risk of demagnetization

[0007] The research on the temperature rise of the permanent magnet synchronous motor involves the coupling analysis of the magnetic field and the temperature field. The general practice is to use the actual measurement of the air gap temperature curve for thermal analysis, and treat the rotor as an independent finite element model. The source of loss is simplified by Model acquisition, the error on the heat source will be an important factor for the inaccuracy of the thermal analysis model, and it is difficult to accurately measure the air gap temperature curve in advance

In terms of temperature rise calculation, most of the traditional calculation methods use empirical formulas to obtain thermal parameters, and take a large approximation to the thermal model, and there is no very general calculation method for accurate analysis

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