Reluctance network method based dynamic model of radial active magnetic bearings

Active magnetic bearings (AMB) are increasingly used in high-speed electrical machines, compressors, turbomachinery, spindles and energy storage flywheels. In order to investigate the performance of these bearings, and especially to develop a reliable control for them, an accurate and computationally efficient bearing model is required. In the model the magnetic nonlinearities due to saturation of the magnetic materials as well as the impact of the leakage flux paths, cross-coupling effects and the eccentric rotor must be considered. Mainly, the analysis and design of AMB are based on two-dimensional (2-D) finite-element method (FEM). Although this method yields a precise determination of the device performance, it is not attractive for dynamic simulations due to its high computational cost. Alternatively, the reluctance network method (RNM) provides satisfactory accuracy compared to the 2-D FEM but with only a fraction of computations. In this paper, a dynamic model for a radial active magnetic bearing is developed using the RNM.