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Linear Switched Reluctance Machine Drives with Electromagnetic Levitation and Guidance Systems
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Many electrically propelled, and magnetically levitated and guided actuation systems (maglev) use either linear induction or synchronous machine topologies. From the cost, reliability, fault tolerance, and phase independence points of view, linear switched reluctance topologies are attractive for transportation application. This thesis investigates a novel topology in which a linear switched reluctance machine (LSRM) propulsion drive is incorporated in the magnetically levitated and guided vehicle. Designs of the LSRM and dc electromagnet, analytical aspects of modeling and dynamics of the vehicle, and closed loop control of propulsion, levitation, and guidance systems are discussed with comprehensive simulations and experimental results. Due to the lack of standard design procedure for LSRM, a novel design procedure is proposed using the current knowledge and design procedure of rotating switched reluctance machines. Analysis procedures for the phase winding inductance, propulsion and normal forces with translator position are developed with a lumped-parameter magnetic circuit model and the results from it are verified with two-dimensional finite element analysis. Extensive experimental correlation of inductance, propulsion and normal forces to validate the analysis and design procedure is presented. For the stable operation of the electromagnetic levitation and guidance systems, which have inherent unstable characteristics, the air gap position and force/current control loops are designed using PID (or PD) and PI controllers, respectively, and implemented and tested. The step-by-step design procedures for each controller are systematically derived. A feedforward compensation strategy for the levitation air gap control is proposed to reject the external force disturbance mainly caused by the normal force component generated in the LSRM propulsion drive system. The reduction of mechanical vibration and hence the enhancement of ride quality is achieved. Extensive dynamic simulations and experimental results for the integrated maglev system are presented with a 6 m long prototype system. Experimental correlation proves the validity of the controller design procedure based on the single-input and single-output model, and shows the feasibility of the LSRM-propelled electromagnetic levitation and guidance systems. A novel maglev topology in which only two sets of LSRMs are utilized to control individually propulsion, levitation, and guidance forces is proposed. One set of the linear switched reluctance actuator produces the levitation and propulsion forces and the other set generates the propulsion and guidance forces. The proposed architecture, thereby, obviates the need for design, development, and implementation of separate actuation systems for individual control of propulsion, levitation, and guidance forces and in contrast to most of the present practice. Further, the proposed system utilizes each of the linear switched reluctance actuation system for producing the propulsion force, thereby giving an overall high force density package for the entire system. The feasibility of the proposed system by finite element analysis is demonstrated.
- Doctoral Dissertations