Loss Calculation And Temperature Rise Research Of Ultra-High Efficiency Asynchronous Starting Pmsm

The shortage of energy supply is an urgent problem to be solved in China.Ultra-high efficiency asynchronous starting permanent magnet synchronous motor(PMSM)is a self-starting PMSM.High efficiency,energy saving and high reliability are the advantages of it.Asynchronous motor can be replaced by it to alleviate energy problems and produce considerable economic benefits.Because of the high power density of PMSM,a lot of heat will be generated during operation,which may threaten the safety of the motor.The premise of studying the thermal problem of the motor is to accurately calculate the loss of the motor,so the research on the loss and temperature rise of the high-efficiency asynchronous starting PMSM can not be ignored.In this paper,an 11 kW high efficiency PMSM with IE4 efficiency is taken as the research object.The main research contents are divided into the following parts:Firstly,based on the design method of PMSM,the asynchronous starting PMSM which meets the performance index of the motor is designed,and the main size design,air gap length selection,stator and rotor punching design of the motor are completed.The electromagnetic field analysis and starting ability analysis of the motor under no-load and rated load are carried out by using finite element software to verify the rationality of the scheme.Secondly,the stator iron loss,rotor eddy current loss,winding copper loss and mechanical loss that may cause temperature rise in the motor are calculated and analyzed.In order to calculate the stator iron loss of the motor,the electromagnetic field in the typical position of the stator core is calculated and analyzed.According to the principle of iron loss separation and harmonic analysis,various calculation models of iron loss are established.It is found that the calculation values of iron loss are the most accurate when considering alternating magnetization,rotating magnetization and magnetic field harmonic at the same time.When studying the loss of the motor rotor,the value and distribution of core loss of rotor,eddy current loss of permanent magnet and eddy current loss of squirrel cage guide bar under different load values are calculated.The mechanical loss and copper loss of winding were calculated.The influence of motor structural parameters on motor loss was analyzed.Then the temperature field of the motor is calculated and analyzed,and the thermal analysis method of the motor is selected.The three-dimensional steady-state temperature field model of the asynchronous starting PMSM is established.On the premise of ensuring the accuracy and rationality of the calculation,the components are treated equivalently,the solutiondomain and boundary conditions of the temperature field are selected,and the equivalent thermal conductivity and heat dissipation coefficient of each part of the model are determined.The heat generation rate of each part of the motor is calculated.The steady-state temperature field of the motor under rated load and no-load condition is calculated.The temperature distribution and the hottest point of the motor parts are obtained.The temperature rise of the motor is within a reasonable range,and the permanent magnet has no demagnetization risk.Finally,the experimental study on the working characteristics and loss of the motor is carried out,and the experimental results are compared with the calculated results in this paper to verify the rationality of the motor design method and loss calculation method in this paper.