Research On Thermal Field Of Inter-turn Short Circuit Fault Of Permanent Magnet Synchronous Motor

Inter-turn short circuit(ITSC)is a common winding fault of the motor,after the fault occurs,it caused the stator winding current increase or motor local overheat,so it affects the distribution of overall temperature field of the motor.If the motor is operated under the fault conditions,the performance of motor will decline,cause damage to the motor and economic losses.In order to research the permanent magnet synchronous motor thermal field in case of ITSC fault,this dissertation took a permanent magnet synchronous motor as the subject of research,a three-dimensional equivalent thermal model was established base on the motor parameters.Through analyzing the losses of the motor were calculated accurately.The shell was segmented along the axial direction and the different conditions were applied to the surface,the heat dissipation of junction box and the eddy current loss of permanent magnet was analyzed.The thermal distribution of the motor under normal and ITSC fault conditions were calculated by finite element method.In order to verify the feasibility and accuracy of the temperature field calculation model and theoretical analysis.The experimental platform was built by rewiring the motor winding,the thermal field data of the permanent magnet synchronous motor were measured.The distribution of thermal field was analyzed before and after the ITSC fault,the bases for diagnosis of the ITSC fault were provide.The performance of permanent magnet was changed with the temperature,according to the thermal field data of the motor,the demagnetization of permanent magnet at different temperatures were researched,the law of demagnetization rate with temperature was obtained.After the ITSC fault,the fault winding current was increased,the direction of the magnetic field was opposite to the other winding,the demagnetization state of the permanent magnet was influenced by the opposite magnetic field.According to the amplitude of no-load back electromagnetic force,the demagnetization state of the permanent magnet was judged,the influence of the demagnetization state under the short circuit fault condition was obtained.If the effective measures were taken,the probability of failure will reduced.In this dissertation,the thermal field of ITSC fault was analyzed,the demagnetization of permanent magnet under the ITSC was researched,the distribution of thermal field under the ITSC fault condition and the demagnetization state of permanent magnet were obtained,the bases for diagnose ITSC fault were provided.