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Evaluation and Comparison of Electric Propulsion Motors for Submarines

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Master's thesis

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The Navy has announced its conviction to make its warships run on electric power through the decision to make its newest line of destroyers propelled with an electric propulsion system. Several ship construction firms and electric motor manufacturers are thus striving to develop enabling technology, including high power density motors. The purpose of this thesis is to evaluate some of the proposed motor designs for use in a submarine. Permanent magnet, superconducting synchronous and homopolar motors are modeled using computer programs. The application of these motors is optimized for submarine propulsion. The use of reduction gearing was not considered. Therefore, only low speed propulsion motors are evaluated. The permanent magnet motor utilized is the classic surface mounted magnet design scaled up to 21 MW with formed, rather than wound, coils. The superconducting synchronous motor utilized is loosely based on a design by American Superconductor and uses equations developed from the doctoral research by James L. Kirtley. The homopolar motor utilized is based on a novel design proposed by General Atomics. For each motor concept, a repetitive optimization algorithm is used in which the design parameters of each motor are randomly generated and the motor attributes are evaluated. The attributes of the resulting motor, such as weight, volume and efficiency, are compared to a database of stored motor designs. If the new designs attributes dominate a previous design, it is included in the database and the dominated design is discarded. After several cycles the optimum motor designs are converged upon. The structure of this algorithm is based on the Novice Design Assistant developed at MIT by J.A. Moses et al..

Subject Categories:

  • Computer Programming and Software
  • Submarine Engineering
  • Electric and Ion Propulsion

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