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Title: Magnetic Levitation Using Tuned LCR Circuits.
Author: Kaplan, B. Z.
Awarding Body: University of Sussex
Current Institution: University of Sussex
Date of Award: 1971
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Experimental and analytical investigations of a relatively new magnetic levitation device ere described. This device uses an electromagnet, which is the inductive port of a resonant circuit. Due to the effects of resonance the electromagnet current is strongly dependent on the position of the suspended object. If the circuit is properly tuned , the average magnetic force acting on the suspended object would be a restoring force similar to that exerted by a spring. This implies that static stability is attainable. The peculiar dynamic instabilities of the device have been reported by others and by the author. In order to understand these instabilities and to help with the design of auxiliary stabilization loops, a method is needed which enables quick analysis. In the systems described in this thesis, the frequency of the supply is much higher than that associated with the mechanical vibrations, and as a result, a direct digital simulation of the equations is inefficient. It is possible to overcome this difficulty by using an approximation of slow varying quantities. Due to the omission of the detailed high frequency oscillations from this new representation, it has been possible to obtain a solution of an example by using only 225 steps of integration. Using the original equations, about a hundred times this number of steps would be necessary. The results obtained by this method agree with those observed in an experimental model. They also agree with analogue simulations. It is known that static characteristics such as the variations of force and stiffness with position can be evalunted by using steady state impedances. It is, however, interesting to note that when the frequency of the supply is much higher than that of the mechanical" oscillations, then the equivalent electromechanical spring constant does not contribute solely to the understanding of static characteristics; it is also associated with the dynamic behaviour of the suspended object. A tuned circuit levitator is a member of a broader family of devices, i.e. "Parametric Electromechanical Systems". Comparison of a levitator to other members of this family enables one to obtain a physical understanding of its dynamic characteristics. Further physical insight is made possible by using a calculation similar to that usually employed when pure electronic parametric amplifiers are analyzed. The results obtained in this way also agree with previous results. Part of this work is concerned with the development of models , This is important for the investigation of technological problems. It is shown that dynamic stabilization of the device is possible by employing relatively simple electronic means. Consequently, tuned circuit levitators are probably more reliable than similar servo suspension systems. Matters related to the constructional geometry of these devices are also discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available