Conference: 한국자기학회 하계학술대회
Authors: Dae-Kee Kim, Jae-Hyun Kim, Dong-Min Kim, Myung-Seop Lim
DOI:
The growing concerns of global scale of pollution and the depletion of conventional energy sources such as fossil fuel caused the interests in alternative energy source. Then, electric motor is applied to various industrial fields to solve these problems. Interior permanent magnet synchronous motor (IPMSM) is one of the motor types. Because the torque density of IPMSM is relatively high compared with other types of electric motor, it is widely used in various appliances. Researches on magnetic material and design technology improved the performance of motor. On the other hand, as the importance of quality of life grew higher, demand for lowering the noise and vibration has increased. Thus, it is important to analyze the vibration generated by electric motor.
The radial electromagnetic force generated by electric motor, acts as the excitation force. This force acts on the teeth of the stator inducing the vibration of whole stator core of motor. Thus, in order to analyze the motor vibration, it is necessary to analyze the radial electromagnetic force. The amplitude and vibration order of radial electromagnetic force mainly affect the aspect of motor vibration. The vibration order of radial force is the spatial harmonic component which indicates the spatial distribution. Because the deformation of stator is inversely proportional to the vibration order, lower vibration order cause the larger motor vibration.
When eccentricity occurs, the vibration order of motor can be changed causing unbalance of radial electromagnetic force. Fig. 1 shows the types of eccentricity. Static eccentricity in Fig. 1 (a) occurs when the rotating axis and the center of rotor are moved simultaneously and while dynamic eccentricity in Fig. 1 (b) occurs when the center of the rotor is moved. In this paper, the changes in vibration order of motor depending on type of eccentricity are discussed by using spectrum analysis shown in Fig. 2. The time and spatial harmonics of radial electromagnetic force is analyzed by spectrum analysis. After that, applying different radial electromagnetic force by different eccentricity type, the deformation of stator is calculated by finite element analysis verifying the effect of changed vibration order.