Novel internal Lorentz magnetic bearing for magnetic bearing gyrowheel

To remedy the limitations of external Lorentz magnetic bearing with poor gas flux density uniformity, an internal Lorentz magnetic bearing for magnetic bearing gyrowheel was presented. The three dimensional finite element method was used for analysis of the gas flux densities of two schemes. The gas flux density rates of internal scheme in circumferential and longitudinal directions were 0.8% and 8.4%, less than that of extern scheme of 15.0% and 23.7%, respectively. The integration method was applied to accurate calculation of internal scheme magnetic resistances segmented by magnetic field division. The magnetic mathematical model of magnetic bearing was established, and the key structure parameters of reverse current stiffness were obtained. Then, by taking shape and structure parameters of internal scheme, the optimal design was achieved through finite element method. The results show that in the case of improvement of gas flux density uniformity the maximum and minimum flux densities in winding region are 0.464 T and 0.427 T, which are increased by 14.6% and 16.0% compared with initial values of 0.404 T and 0.368 T, respectively. According to optimization results, an internal Lorentz magnetic bearing is manufactured and its gas flux density and current stiffness are measured. Tests have a good agreement with design results, which has great significance in the design of Lorentz magnetic bearing.