Study On Calculation Method And Influencing Factors Of Copper Loss And Rotor Eddy Current Loss Of High-speed Permanent Magnet Motor

Due to the advantages of small size,high efficiency and good control performance,highspeed permanent magnet motors are currently widely used in industrial drives,precision manufacturing,aerospace and other fields.However,the temperature rise of motors is increased by the large loss density,affecting motor life.In this thesis,AC copper loss and rotor eddy current loss of high-speed permanent magnet motor are calculated,and finite element analysis is used to analyze the effect of factors on loss,and reference is provided for the preliminary design of high-speed permanent magnet motor.The main research contents are as follows:Firstly,skin effect,proximity effect and circulating currents effect in strands caused by high frequency current are deeply studied.In order to accurately represent AC/DC copper loss ratio of motor and save calculation time,by comparing calculation results of AC/DC copper loss ratio of different winding models,the one-slot model of same phase winding is determined as a simplified analysis model.Secondly,the effect of conductor position,conductor cross-sectional shape and strands number are studied.At a certain current frequency and amplitude,the relationship between AC copper loss with the diameter of conductor is studied;The influence of winding placement on AC/DC copper loss ratio is studied.The multi-strands conductors are modeled in detailed.The allocation of strand current is compared and winding arrangement that can effectively suppress AC copper loss is summarized.Then,experimental principle and process are briefly described.The relationship of AC copper loss with current frequency and wire diameter is analyzed by magnetic core coil experiment.The influence rule of conductor position on AC copper loss is indirectly obtained by iron core coil experiment.The accuracy of finite element analysis results is further verified.Finally,the generation mechanism of rotor eddy current loss is analyzed and analytical calculation model is established.The influence of factors on rotor eddy current loss is analyzed when motor is under load.The impact of circumferential section of permanent magnet on rotor eddy current loss is studied;The effect of air gap length on rotor eddy current loss is analyzed;The harmonic content of air gap magnetic flux density in parallel magnetization and radial magnetization is compared.The impact of magnetization field pattern on rotor eddy current loss is studied;The influence rule of distribution of sheath material on rotor eddy current loss is studied.The change relationship between rotor eddy current loss with sheath conductivity is further analyzed;The effect of carrier ratio on rotor eddy current loss is studied when PWM source is applied.