Dynamics and Control of an Active Magnetic Bearing-Rotor System with Time Delay

Time delay in digital control loop, which is usually neglected in most of the research in electromechanical systems, may have great influence on the performance of high-speed active magnetic bearing (AMB) systems. In order to study time delay’s effect on system stability and dynamics, a 2-degree rigid rotor-magnetic bearing system was employed and the stability boundary of time delay on this system was discussed. Then a control law of compensation for time delay was presented and a state predictive module was introduced into closed-loop control system. Simulation results showed the control performance degraded owing to computing time delay, and the system became unstable when time delay exceeded the upper boundary. Then via the addition of time delay compensating module, the control performance is well improved. It is clearly indicated that it is necessary to take time delay into consideration when the dynamics and control problem of high-speed AMB system is studied. The control strategy presented in this paper can compensate the negative effect of delay effectively.