Design And Research Of Electromagnetic Force And Vibration Of Double Three-phase Induction Motor

With the improvement of people's requirements for motor reliability,the advantages of multi-phase motor are highlighted.The multi-phase motor has the characteristics of achieving short-term stable operation under the condition of phase-absence,but the vibration phenomenon still exists under the condition of steady-state operation with fault-tolerant mode.Therefore,electromagnetic vibration problems of multi-phase induction motor need to be studied in depth.In this paper,double three-phases induction motors were studied,its design method was studied at first,and its electromagnetic forces under operation conditions in rating state,phase-absence state and fault-tolerant state were studied respectively,and its structural vibration characteristics was analyzed also.After vibration reduction structure of the double three-phase induction motor was studied,the motor with 30-degree offset winding structure was selected as the best one,according to the comparing and analyzing results of the harmonics and torques of the double three-phase induction motors with two different winding structures.The test data were obtained by carrying out the test of the two different motors operating under the fault-tolerant steady-state condition.After comparative analysis,it is verified that the double three-phase induction motor can produce up to 49% of the rated torque during fault-tolerant steady-state operation condition,and the motor can operate safely and steadily.The effect of electromagnetic force on the motor was analyzed.Combined with the analysis of finite element magnetic field and Maxwell tensor method,physical model of a double three-phase induction motor was established,formula of its electromagnetic force density was derived.The data of tangent electromagnetic force density and radial electromagnetic force density of the dual three-phase induction motor were derived when it is operating in rated condition,phase free condition,and fault tolerance operation mode,were obtained.The radial electromagnetic force density spectrum and magnetic density at radial air gap position were analyzed with finite element method,data were obtained through calculation and analysis,and the change regulation was summarized through comparisons.These work will be a foundation for further study of the electromagnetic force impact on the vibration of the structure of the dual-three-phase induction motor.The structural vibration characteristics of the two-phase induction motor when fault-tolerant steady-state operation were studied.The difference between the two-phase three-phase induction motor stator iron core two-dimensional and three-dimensional modal analysis model was analyzed,the role of the machine seat and end cover in the modal analysis model of two-phase induction motor was analyzed,and a modal analysis model of the whole machine which is close to the actual condition was established.The natural frequency calculation and data are obtained on the different modal analysis models of the dual three-phase induction motor,and the frequency points that produce peaks in the radial force density spectrum do not coincide with it,so the conclusion that the two-phase induction motor will produce a smaller vibration is obtained.Through the comparative analysis of vibration test data,the design rationality of the structure of the two-phase induction motor relative to vibration is verified.