VIBRATION CONTROL FOR A HIGH-TC SUPERCONDUCTING NONLINEAR LEVITATION-SYSTEM

In the present paper the modelling and control of a high-Tc supercondu cting levitation system are discussed. First, the analytical expressio ns for obtaining the non-linear levitation force, given by the present author, are clarified; and then a vibration control method is present ed in which feedback currents involving frequency weights are used. In the method, the square of the displacement in the frequency domain is taken as a cost function. Optimal coefficients of the transfer functi on of the controller are obtained by minimizing the cost function. Hen ce, the spillover instability due to the non-linear vibrations will be reduced. Numerical calculations have been carried out for some typica l problems. To validate the present method, experimental tests have al so been carried out. (C) 1997 Academic Press Limited.