Researches On Behavior Of Noise And Vibration In Permanent Magnet Servomotor For Elevator

Researches on behavior of noise and vibration in permanent magnet servomotor for elevator are conducted using the software of finite element method in this dissertation. The main aspect of electromagnetic noise and vibration in permanent magnet servomotor is presented.Calculation of radial electromagnetic force causing by vary harmonic magnetic field in air gap is done in 9.5kW permanent magnet servomotor for elevator. Because of the radial electromagnetic force creating in air gap of magnetic field on stator tooth is the main reason on electromagnetic noise and vibration in PMSM, extracting radial magnetic flux density and calculating radial electromagnetic force are important in analysis of electromagnetic field. By means of 2-D electromagnetic field calculation and 3-D electromagnetic field calculation of servomotor, it shows that magnetic flux density waveform in the air gap relates to magnet configuration, current harmonics, wound distribution, the number and formation of tooth slot of stator and rotor and power angle. The principle resulting in radial electromagnetic force in PMSM is deduced.According to loading obtained from analysis of electromagnetic field, the structure of PMSM transient analysis is presented. The radial electromagnetic force loading on stator tooth in motion electromagnetic field is applied to 3-D model of PMSM. After analysis of structure, the response of all nodes is obtained. Modal analysis in structure of electrical motor is an important method to determine whether the resonance of the structure can be induced under radial electromagnetic force. Various modal shape of 9.5kW PM servomotor for elevator are calculated by 3-D finite element method. The improved scheme is presented in structure of PMSM.In the transient analysis of 2-D sound field on PM servomotor, the loading obtained from analysis of electromagnetic field is applied on stator tooth also. The model of fluid-structure coupling interface and fluid border is established respectively. The response of structure and mediate nodes sound pressure, displacement is gained by transient sound field analysis, which is the base of the prediction of noise value of PMSM.Through experimental investigation of PMSM, it shows that the switching frequency of pulse width modulation (PWM) current from inverter is a main factor affecting upon sound radiation of PMSM in control system of permanent magnet motor.