Vibration Characteristics Study On Fifteen Phase Induction Motor

High-power frequency converter and modern variable-frequency drive technology make high-reliability and high-torque-density multi-phase motor become the first choice of marine electric propulsion system,among which 15-phase low-voltage high-power induction motor is the most engineering application prospect.The motor of the ship is small in size and light in weight,and the corresponding structure is compact and light,the rigidity is poor,the anti-vibration performance is not good.The motor vibration is putted forward high demands to reduce interference with other devices and improve stealth.In this paper,the vibration mechanism of 15-phase induction motor is studied,the vibration reduction method is founded,and the design of the motor satisfying the application requirements is of great practical significance.Because china's 15-phase induction motor research started late and high development costs,research was focused on basic theory and program design,the motor vibration and physical development are very less.Based on the study of electromagnetic excitation theory of induction motor,this paper analyzes the mechanism of radial electromagnetic excitation,and analyzes the three factors of vibration characteristics : order,amplitude and frequency.Based on the characteristics of fifteen-phase induction motor,the vibration characteristics of the excitation force under non-sinusoidal power supply are studied.For the first time,the harmonic magnetic fields generated by different harmonic exciting current are interacted to produce more complicated exciting force.It is found that the important means to weaken the vibration of the motor is to raise the order of the exciting force and reduce the amplitude.The influence of slot coordination on the order and frequency of exciting force is analyzed,and the optimal slot coordination on vibration for the 15-phase 12-pole induction motor is 180/208.Based on ANSOFT,the vibration force and performance parameters of the 15-phase induction motor are calculated and compared with the performance parameters calculated by the company's mature motor design program,which proves the accuracy of numerical calculation of the exciting force indirectly.The structural vibration characteristic of the motor is studied: Vibration mode and natural frequency.It is possible to avoid the resonance of the motor by avoiding the same frequency as the natural frequency close to the exciting force.Based on ANSYS,the modes of stator,rotor and complete machine are studied.The influence of the structure parameters on the natural frequency of the stator is analyzed and compared.The results show that it is effective to change the natural frequency of the stator by changing the outer diameter of the stator,the inner diameter of the stator and the axle stiffener of the motor frame.In this paper,the stator mode test and the whole motor vibration test are carried out.The experimental results and the theoretical calculation and analysis error meet the engineering application requirements.The developed 15-phase induction motor has excellent vibration performance to meet the design requirements.