Practical results of ADRC applied to Radial Position Control of a Bearingless Induction Machine

A Bearingless Induction Machine (BIM) with split winding has an operation strongly dependent on well-designed control routines, since the magnetic shaft suspension is a naturally unstable system. Furthermore, this system is multivariable, non-linear, and it has coupling between variables. Because of this, linear position usually presents some limitations in dealing with the system complexity. In recent years the Active Disturbance Rejection Control (ADRC) has been used to control several types of systems and has shown good results in the control of systems with strong uncertainties and nonlinearities. The main idea of the ADRC is to group all the uncertainties of the plant, such as non-modeled dynamics, external disturbances, and variations in parameters, as an additional state variable to be estimated in real-time using the input and output variables. Thus, the additional state variable can be estimated and compensated in the control loop. In the work of Silva (2021) the control of a BIM with split winding with ADRC as position controller was proposed and results from a simulated system were shown. In this work, the results obtained by Silva (2021) were improved with experimental results, using a simplified version of the ADRC controllers and a BIM with a reduced driving scheme. The results showed it is possible to use the ADRC with a split winding BIM and will be the basis for future improvements on the control strategy.