Research On Reliability Of Permanent Magnet Synchronous Motor With High Torque Density

Permanent magnet synchronous motors have high torque density,high efficiency and high dynamic response,and are therefore widely used in industrial fields.Aiming at the actual demand of higher torque density of permanent magnet synchronous motor,the performance improvement of permanent magnet synchronous motor and exploring the performance limit of permanent magnet synchronous motor have become one of the hot issues in the field of electr ic motor.However,due to the weight reduction of the motor and the design of the high output torque,the electromagnetic load of the motor is greatly increased,which brings about problems in the research of motor reliability.In this paper,the reliability evaluation of high torque density permanent magnet synchronous motor is taken as the focus problem.The failure mechanism and failure state of high torque density motor,the influence of internal stress field of the motor on the reliability of the motor and the high torque density motor system Reliability modeling has been studied and analyzed accordingly.Firstly,the design trend of high torque density motor is analyzed,and the permanent magnet and winding insulation are extracted as the main failure parts of the motor;the failure mechanism is analyzed for the permanent magnet,through the temperature field,DC demagnetizing magnetic field,magnetic path reluctance,permanent magnet size And the influence of alternating magnetic field on the failure of permanent magnets,the failure mechanism and failure law of permanent magnets are summarized.The typical stresses for the insulation failure of windings are temperature stress,electrical stress and mechanical stress.The simulation of motor working state by component failure is clear.The fault state of the motor.Secondly,on the basis of clarifying the failure stress inside the motor,the internal temperature field of the motor and the working performance of the permanent magnet are calculated.The thermal network calculation model of the permanent magnet synchronous motor is established.According to the performance characteristics of the permanent magnet,the permanent magnet is magnetically stable.The squareness of the squareness and the coefficient of the demagnetization knee are calculated;the magnetic stress of the Halbach motor structure used to improve the torque density of the motor is checked.Then,the permanent magnet and the winding insulation in the motor are used to perform the multi-physics coupling failure model.For the performance degradation experiment of the permanent magnet,the failure model of the permanent magnet coupled with the temperature field,the demagnetizing field and the AC magnetic field is constructed,and the different stresses are obtained.Under the field,the acceleration factor of permanent magnet failure rate.By considering the electrical insulation aging and thermal aging of the winding insulation,the winding insulation life model under two stress couplings is obtained.The motor temperature and demagnetization are optimized for the basic motor parameters.Comparing the shape of the permanent magnet of the motor and the size of the stator slot,the motor reliability is optimized.Finally,the reliability of motor integration is modeled.By determining the internal stress field level of the motor,the failure rate of each component is calculated.According to the influence of motor component failure on the working state of the motor,detailed division is carried out.According to Markov theory,the reliability of the motor system is modeled.The design was carried out,and the reliability of the motor was optimized through experiments,and the relationship between torque density and motor reliability was explored.