Universal Model and Control Framework for Bearingless Motors with Combined Windings

This paper presents a model and control framework for bearingless motors that is generalized for all types of combined-winding configurations with six phases. The aim of the paper is to facilitate the rapid implementation of MATLAB Simulink models of the electric behavior (voltage/current) and mechanical behavior (force/torque) of radial-flux, non-salient bearingless motors with combined windings. Bearingless motor developers will find this to be a useful guide for creating control simulations and understanding how changes in the number of motor/suspension poles and winding type impact their control architecture. The paper shows how the provided universal model/controller can serve as the starting point and baseline for establishing a control simulation environment that is later refined to capture the architecture-specific aspects of a practical bearingless motor control system. A case-study machine with a p=7 motor and ps=8 suspension pole-pairs is introduced and the universal controller concept is validated through simulation and experimental results.