Using electric magnetic suspension, magnetic levitation (MagLev) systems have been widely applied in various industries for their great characteristics such as non-contact, noise free, cleanness, high speed transportation, and so on. Especially, superconducting-hybrid electro-magnetic suspension (SH-EMS) is increasingly receiving attention in high-speed transportation because of their property to compensate the instability of MagLev systems. The SH-EMS necessarily requires the fixed apparatus and robustness against the mechanical and electrical disturbances such as sensor noises, current disturbance, levitative force fluctuation in order to prevent quench. Even though the existing robust and optimal control methods have been researched in control engineer, there still exist many challenges on designing and implementing the controller due to their complexity and set-point tracking as compared with conventional proportional-integral-derivative (PID) control. In this paper, we propose the enhanced PID control method with full-order observer, called Kalman filter in order for the noise rejection and good-command following. Composed of Kalman filter and optimal control law, the proposed compensator is tuned for sensor noise rejection and current disturbance reduction. And the total servo controller for tracking the desired air-gap position including the designed compensator matched to the conventional PD controller is determined by convex combination method (CCM) such that the performances of time and frequency domains have the convex properties. The main contributions of the proposed method are summarized as follows: (i) The proposed method provides the intuition to control engineers to apply the traditional controller with disturbance rejection filter and expect the controlled responses of MagLev state in time- and frequency domains by CCM. (ii) The control parameters are explicitly determined by the proposed linear matrix inequality optimization problem to solve CCM. (iii) The proposed multi-loop controller has degree-of-freedom to independently consider various design performances in time and frequency domains.
|Submitters Country||Republic of Korea|