Eddy current effect in a magnetic bearing model

Eddy current problem in a simple magnetic bearing model is treated. Such a problem is very important in the case when solid steel is used as a shaft material. We have made the calculation about eddy current effect on a hypothetical, simplified model by finite element method. Diagrams of flux distribution in both the airgap and the shaft material are obtained at various rotor speeds. We can clearly see how eddy current induced in a shaft affects main flux of electromagnets. The form of current distribution for producing main flux of electromagnets is taken as both sinusoidal and rectangular. We have also calculated the characteristics of attractive force and counter torque vs. rotor speed. This model is suitable for examining effects of various parameters. No suspicious rugged aspects were perceived in our calculation results. This confirms that our way of making subdivision is good. Our results make it possible to predict the realistic performance tendency and to know the working region less affected by eddy current.