Browsing by Subject "Magnetic suspension"
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Item Controlled electrodynamic suspension vehicle damping(2006-05) Knierim, Glenn Auld, 1970-; Driga, Mircea D.Commercial application linear motion magnetically levitated, maglev, bodies are inherently unstable owing to minimal large magnitude or prolonged oscillating disturbance natural damping. Induced vibrations into large inertial, magnetically levitated bodies experience resonance under certain operating conditions. Maglev vehicles typically incorporate a non-magnetic ancillary damping suspension system as compensation. Maglev designers desire an efficient, solely magnetic based damping system without auxiliary compensation for these large inertial vehicles, but no effective system has presented itself. This paper investigates the unstable nature of a maglev electrodynamic suspension, E.D.S., system. Electromagnetic solenoid coils operating in concert with an appropriate control law offer this solution. A hierarchy of controlled, electromagnetic damping suspension systems is theorized and analyzed and in one case designed, fabricated, and tested. These designs range from a single degree of freedom, D.O.F., maglev suspension to a dynamically coupled six D.O.F. maglev suspension. Solenoid coils form the electromagnetic damping prime mover hardware. Soft computing optimal nonlinear control forms the final electromagnetic damping control kernel for this proof of concept paper whereas soft computing adaptive nonlinear control forms the final electromagnetic damping control kernel for a proposed final system solution.Item Design and electrodynamic analysis of active magnetic bearing actuators(2003-05) Pichot, Mark Allen, 1956-; Driga, Mircea D.For more than a century, engineers have imagined bearing systems that use magnetic fields to levitate rotors in rotating machines, eliminating contact between bearing surfaces. In the past twenty-five years, magnetic bearing systems have moved from laboratory novelty to an accepted industrial product, and are now being used in an impressive variety of applications. This dissertation deals with the development and verification of design codes for permanent magnet bias, homopolar magnetic bearing actuators. A design code using magnetic circuit analysis is developed that can provide quick evaluation of candidate bearing actuators. Non-linear material properties are represented, and force versus current bearing characteristics can be calculated as a function of operating speed. Details of code development and description of a user interface created with a commercially available spreadsheet program are presented. To verify magnetic circuit design code predictions, three-dimensional finite element analysis is performed for a magnetic bearing system of interest. For experimental verification, an inside-out topology test bearing actuator and testing fixture were designed and fabricated in which bearing parameters were directly measured. Test results are presented and compared to theoretical predictions of the circuit analysis code and finite element program. In high-speed rotating machines, rotating losses are a prime concern because heat transfer mechanisms to remove rotor heat are limited. Losses inherent in permanent magnet bias homopolar magnetic bearings are discussed and the dependence of losses on bearing geometry is explored. Studies to reduce rotor losses by optimizing stator winding slot geometry are presented. Finally, a thrust-bearing concept designed to further reduce bearing losses is evaluated. In this concept, the static rotor weight of a vertical-axis machine can be supported by bearing actuator bias fields, minimizing required control effort. This concept holds the promise of reducing actuator power input and bearing losses, thus increasing bearing system efficiency.