Adaptive and Non-adaptive Variable Structure Controls with Sliding Mode for Active Magnetic Bearings (AMBs) and Magnetic Levitation (MAGLEV) Systems: A Comparative Study

In this paper we will present on two methods for high performance active magnetic bearings (AMBs). These methods based on robust Variable Structure Control (VSC) with sliding mode in non-adaptive and adaptive cases. Our approach combines two simple architectures often referred to as Dynamic Feedback Linearization (DFL) and recent advances in robust control design techniques to form a new approach for AMB for two cases. The procedure enables the designer to explicitly define the desired closed loop dynamics and enables the design of a robust stabilizing controller that forces the system dynamics to the specified desired dynamics, despite gravitational and centrifugal disturbances, modeling uncertainties, and variations in mass, moments of inertia, radii of eccentricities and center of mass of the rotor. Our design hangs the magnetic bearing on gravitational parabolic sliding surface by switching electronics and sliding mode control components. Thus, electromagnets do not constitute cross forces on rotor shaft that affects against each other. This operation guarantees the lowest power losses, by considering low bias currents method that the currents affects against. The methods also guarante both stability and performance robustness and enable the design for other unstable magnetic levitation systems. When the methods are compared with each other, the results in adaptive case are more efficient about high speed and wide range of parameter uncertainties.