Dynamic Stabilization of AC Magnetic Suspension Using Magnetic Resonant Coupling by Transmitted Power

The AC magnetic suspension system using magnetic resonant coupling is dynamically stabilized by a DC suspension mechanism operated by the power transmitted to the floator through the magnetic resonant coupling. The target AC magnetic suspension system has a self-stabilization property; restoring force is produced without any active control. However, it is dynamically unstable because slightly negative damping is also produced when the stator is fixed. Therefore, it is necessary for dynamic stabilization to add positive damping to the floator. A DC magnetic suspension is installed in parallel with the AC magnetic suspension to generate positive damping without any active control. The developed system has a pair of AC electromagnets for positive stiffness and another pair of DC electromagnets for positive damping. First, the coil of the DC electromagnet in the stator is shunted. However, it is experimentally shown that negative damping is produced because the latter pair also has a self-stabilization property; the force increases as the gap increases. Then, a bias voltage is applied to the DC electromagnet on the stator to make the stiffness negative. As a result, stable suspension is achieved without any active control in the developed system.