Research On Loss Of High-speed Permanent Magnet Motor Based On Field Circuit Coupling Analysis

Due to the advantages of small space,small vibration and noise,fast response speed,and high operating efficiency,high-speed permanent magnet motors are widely used in medical cutting,flywheel energy storage,military power supply,space shuttle and many other fields However,its higher frequency and the large number of harmonics generated by the inverter power supply greatly increase the loss and temperature rise of the motor.In response to these problems,this thesis takes a 7.5kW,15000r/min high-speed permanent magnet motor as the research object,the coupling analysis of the control circuit and magnetic field driven by SPWM,the calculation of core loss and eddy current loss,and the simulation of the motor temperature field In-depth research,the main research contents are as follows:Firstly,a field-circuit coupling joint simulation model is built in Simploler and Maxwell,The magnetic field distribution at condition of sinusoidal power supply and SPWM power supply is analyzed,and the influences on phase current harmonic distribution and distortion rate are calculated under different carrier ratios and modulation ratios.Meanwhile,the changes of permanent magnet eddy current loss,sheath eddy current loss and stator core loss of high-speed permanent magnet synchronous motor are calculated under different control parameters.Secondly,the stator iron loss,rotor eddy current loss and winding copper loss of high-speed permanent magnet synchronous motor are calculated.Analyze the mechanism of iron loss,use two methods for semi-analytical calculation of iron loss,consider the iron loss calculation of alternating magnetization and rotating magnetization,consider the iron loss calculation under the combined action of two kinds of magnetization and harmonic magnetic field,use two methods The iron loss result of the comparison with the iron loss calculation based on SPWM power supply is compared.According to the theory of the electromagnetic field of the motor,the eddy current loss of high-speed permanent magnet motor is calculated by the analytical method in the rectangular coordinate system,and the copper shield layers of different thicknesses are used to simulate the eddy current loss of each part of the rotor,and the influence of the copper shield layer on the eddy current loss is analyzed.The effects of skin effect and proximity effect on the copper loss of high-speed permanent magnet synchronous motors are analyzed,and the copper loss of motor windings studied in this thesis is calculated.Then,based on the heat transfer theory and thermal analysis method of the high-speed motor,the equivalent thermal path analysis model of the high-speed motor is built based on the Motor-CAD simulation software,the thermal conductivity and heat dissipation coefficient of each material are added,and the boundary conditions of the high-speed motor are reasonably solved.The components are subjected to three-dimensional temperature field simulation to analyze the influence of different factors on the temperature rise,including the influence of the speed of the spiral water cooling water on the motor temperature rise.Based on the calculation of the eddy current loss of the permanent magnets,the stator windings with different thicknesses of copper shielding layer are explored The effect of temperature rise with permanent magnets.Finally,the experiments on the working characteristics and loss temperature rise of the high-speed permanent magnet synchronous motor prototype were carried out.The actual loss of the motor and the temperature rise of the winding end,shaft,and casing were measured.Compared the previous calculation results with the calculation in this thesis to verified the correctness of the simulation.