Design and Implementation of Modern Controls for Drive and Suspension of a High Speed Double Conical Bearingless Motor on a Real-Time System

In this work, modern control approaches for drive and suspension of a high speed double conical bearingless motor are designed. Firstly, the air gap flux density and the forces acting on the rotor are analytically calculated. Subsequently, an elaborate model of the magnetically levitated rotor is developed, which considers the non-collocation of position sensors and levitation windings as well as the presence of angular motion. Three different control approaches are designed and simulated. The first approach comprises a state controller augmented with integral action, with which the closed loop dynamics are freely defined after pole placement. The other two approaches concern Linear Quadratic Gaussian and Model Predictive control. The pole placement control approach is tested successfully on the test bench with the real motor. Sinusoidal disturbance forces, with the rotational frequency, can cause large rotor orbits and may drive the inverters to their limits. For this reason, two synchronous filtering control strategies are developed. Using Imbalance Force Compensation, the rotor can be driven with low orbits at relatively low speed and using Imbalance Force Rejection, the rotor can be driven with low levitation currents at high speed. The control performance is evaluated by measurements and the measured frequency response of the closed loop system is presented