Four Quadrant Control of Rotor Displacements of Bearingless Switched Reluctance Motor under Eccentric Fault Conditions

Abstract

ABSTRACT The objective of this study is to align the rotor position at the center and maintain less eccentric rotor displacements when bearingless switched reluctance motor (BSRM) is subjected to different loads. In this paper a PID controller is proposed which maintains a stable magnetically levitated rotor position and displacements even on the application of sudden loads to the rotor shaft. As a first step, the rotor is displaced in the four quadrants in the air gap and is successfully pulled back to the center position with the help of the proposed suspension PID controller along with asymmetric converter, hysteresis controller, and rotor displacement sensors. The second step is to run the motor at rated speed by sending phase currents through the PI controller along witha phase hysteresis controller. The third step is the sudden application of torque and suspension loads to the rotor owing to which, the rotor is subjected to eccentric displacements. However, due to control action in suspension phase current, it is pulled back quickly to the center position. The change of suspension loads has a negligible impact on the torque winding current, net torque, speed of the motor, hence the decoupling control is possible between torque and suspension force control. Simulation studies are conducted in all the cases and the obtained results clearly indicate that the suspension winding forces, suspension currents and rotor displacements in both X and Y-directions are in stable condition.