Study On The Dynamic Characteristic Of Magnetic Suspended Flywheel Rotor

Flywheel energy storage is an ancient way of energy storage. The technology did not have any breakthrough before because of many bottlenecks. Until 20th century, because the technology of composite material, magnetic bearing and electronics had enormous development, the flywheel energy storage would bring a revolution about the way of energy storage.Magnetic flywheel battery has advantage of storing more energy than chemical battery, fast charging and discharging, long life, and without any pollution, etc. It has the vast research and development prospects. The stability of magnetic flywheel rotor is the basic condition of flywheel energy storage. Excellent dynamic characteristics of the flywheel rotor gives full play to the advantage of flywheel energy storage. So study on the dynamic characteristics of the flywheel rotor is an important content of flywheel energy storage system.Firstly, this article studies the structure of magnetic flywheel energy storage system, including the design of magnetic flywheel rotor, magnetic bearing, control system, and vacuum and lutation. And analyze the stress of flywheel rotor, the line distribution of magnetic field. Preliminary discussed the design theory of magnetic flywheel energy storage system.Construct the model of rigid flywheel rotor considering the gyroscopic effect and non-concurrent installation of sensor and magnetic bearing. Analyze the nature frequency of flywheel rotor under decentralized PD control. And analyze the flexible flywheel rotor with transfer matrix method. Regard the parts on the axis as additional mass. Calculate the eigenfrequency and vibration mode of free flywheel rotor and elastic supported flywheel rotor. Meanwhile, analyze the relationship of complex stiffness, damping and speed. At last, analyze the influence of magnetic bearing span and overhang length on the rotor's natural frequency.Furthermore, this article studies that the gyroscopic effects have an influence on the system's zeros and poles. The simulation results shows that the pole-zero move to right of s-plane with the increasing of gyroscopic effect. Gyroscopic effect is the main reason of instability of magnetic flywheel energy storage system. The cross feedback control which use cross-coupling term to offset gyroscopic term can compensate gyroscopic effects. The linear quadratic optimal feedback control can compensate gyroscopic effects which obtain the state feedback matrix when quadratic function getting the minimum value. The simulation results shows that cross feedback control and LQR control can make flywheel rotor have better dynamic characteristic. At last, the article analyzes the unbalance response with LQR control.