A motor for an electric vehicle has a stator core and a coil bonded with insulating varnish. The Impregnation of varnish in the stator and at the coil end greatly affects the vibration characteristics of the stator. In this paper, the experimental modal analysis of the sample stator was carried out to measure the vibration characteristics, and a vibration analysis model of the stator with the finite element method was developed.
The laminated structure of an electromagnetic steel plate constituting a stator is modeled by anisotropic material properties. The joint stiffness of the varnish which connects the stator and the coil is modeled. We also modeled the varnish applied to the coil end. We carried out eigenvalue analysis and frequency response analysis. The simulation results are basically consistent with the experimental mode shapes and natural frequencies under 1000 Hz.
The effect of the varnish impregnation range between the electromagnetic steel plates of the stator on the vibration characteristics was investigated. The natural frequencies of the first and second mode which is deformed into an oval shape in the stator cross section are increase as the varnish impregnation range is wider. The response level around the stator at excitation point also increases. In addition, vibration analysis was performed by changing the varnish coupling stiffness of the coil end, and it was confirmed that the bond strength of varnish at the coil end has a large effect on the natural frequency of the stator.