Current control method for magnetic suspension system

Based on time optimal control, variable structure control and online identification theory, a three-step current control algorithm is developed to improve the response speed and precision of the magnetic suspension actuator, i.e., adopting time optimal control approach to track the current as quickly as possible. The ideal current can be obtained with the variable structure control strategy according to the tracking error, and the control voltage keeping the setting current can be determined on the basis of the coil parameters from online identification. The constraint relations of the system hardware and the current response are also derived. The current tracking, step response and amplitude frequency characteristics experiments of the magnetic suspension ball demonstrate that the magnetic suspension system enables to respond to the input current in the shortest time with the proposed algorithm, and the bandwidth is expanded to improve the system.