Model-based predictive control for a compact and efficient flywheel energy storage system with magnetically assisted bearings

A compact and efficient flywheel system is proposed in this paper. The flywheel acts as the rotor of the drive system and is sandwiched between two disk-type stators. A combination of active and passive magnet bearings allows the rotor-flywheel to spin and remains in magnetic levitation. It is a multi-variable, nonlinear, and sensitive system. The conventional PID controller is not effective for such a system operating at very high speed. To achieve better control performance, a novel model-based predictive control (MPC) approach is introduced. The MPC method can pre-calculate the system behavior, and can be robust against model-mismatching and unexpected dynamics. The simulation results have been obtained and compared with the conventional PID control. The results show that the stability, sensitivity and robustness of the MPC approach are superior to PID control for the proposed flywheel system.