Loss Calculation And Efficiency Optimization Of High Temperature Permanent Magnet Synchronous Motor

The working environment of high temperature permanent magnet synchronous motors is harsh,and the requirements for low-loss and high-efficiency are more urgent than those in normal temperature environments or ordinary working conditions.Therefore,it is very important to carry out the accurate calculation of the loss and efficiency of the high temperature permanent magnet synchronous motor,and the optimal design of the motor.Changes in the electromagnetic properties of motor cores,windings,permanent magnets and other materials in a high temperature environment reduce the accuracy of the existing loss model,and the motor efficiency deviates from the optimal design.In order to accurately calculate the loss of high temperature permanent magnet synchronous motors and improve the performance of permanent magnet synchronous motors,this thesis carries out research on the calculation of high temperature permanent magnet synchronous losses and the optimization of efficiency.The main contents are as follows:The test platform of material properties in high temperature environment was built to test the motor core material properties,and the B-H curve of the core material under high temperature environment was obtained,the magnetization and loss characteristics of the core material were revealed,and the influence law of temperature on the magnetization and loss characteristics of the core material was summarized.Combined with the test data and the Bertotti separation model of iron loss,the calculation models of total iron loss and separation iron loss considering temperature effect are established by using the method of data fitting,which lays a foundation for the design of high temperature permanent magnet synchronous motor.The change rule of DC and AC copper consumption with temperature was analyzed,based on the Dowell and Ferreira one-dimensional analytical model of AC copper loss,an accurate calculation model of AC copper loss considering temperature effect was deduced and established by using Taylor series expansion and ignoring higher order terms.Using Simplorer and Maxwell software,a field-circuit co-simulation model was built to further study the variation law of AC copper consumption of windings considering inverter current harmonics.The above calculation model of AC copper consumption was modified to improve the calculation accuracy of copper consumption.Simulation and experimental methods were used to verify the correctness of the model and the accuracy of the calculation results.The high temperature characteristics of permanent magnet materials were analyzed,the generation mechanism of eddy current loss of motor rotor was clarified,the change trend of eddy current loss under high temperature environment was predicted,electromagnetic field calculation by using analytical method and finite element method was carries out,the change law of rotor eddy current loss with temperature was reveals,and the calculation model of rotor eddy current loss considering temperature effect was established.The influence rules of high temperature environment on the above motor material characteristics and related losses were summarized.The variation trend of motor efficiency under high temperature environment was analyzed based on the efficiency function,and the mapping relationship between temperature and motor efficiency was obtained.Based on the precise calculation model of loss considering temperature effect and the efficiency ratio theory of induction motor and transformer,the loss distribution principle of high temperature motor was determined.Finally,the efficiency of the example motor was optimized to verify the correctness of the principle of loss distribution.