Accession Number : ADA187800


Title :   A Comparative Study of Various Electric Propulsion Systems and their Impact on a Nominal Ship Design


Descriptive Note : Master's thesis


Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF OCEAN ENGINEERING


Personal Author(s) : Davis, James C


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a187800.pdf


Report Date : Jun 1987


Pagination or Media Count : 207


Abstract : Computer programs which model synchronous, permanent magnet, and induction machines incorporate an optimization algorithm which converges on lowest weight, volume, and inefficiency. Machine designs for high and low rmps are performed, with a varying number of pole-pairs. The machine designs are analyzed to find the optimum combination of generator and motor for inclusion in a naval ship propulsion system. The three ships used for the study are: a baseline mechanical transmission ship, a ship retaining the same sub-division as the baseline but with the electric machinery, and an electric transmission ship with subdivision and machinery box arrangement chosen to benefit from the inherent arrangeability of electric transmission. The two generator/motor combinations used in the final ship analysis, both employ a 3600 rpm, six-pole synchronous generator, which turns at the shaft speed of the prime mover. One combination uses a 180 rpm, direct-drive, 16-pole synchronous motor, and the other an 1800 rpm, geared, 8-pole synchronous motor. Power converters are used in both combinations to control motor speed. The geared combination in the rearranged ship demonstrated the best endurance speed efficiency, reducing the endurance fuel load by 18%, while maintaining the maximum and sustained speed of the baseline ship. The savings in ship volume translated to an additional twenty Tomahawk missile cells in the rearranged ship. When the fuel load was held at the tonnage of the baseline ship, endurance range increased as much as 25%. Permanent magnet machines were not competitive in this study due to their high weight and volume.


Descriptors :   *ELECTRIC PROPULSION , *MARINE PROPULSION , VELOCITY , COMPUTER PROGRAMS , ALGORITHMS , CONTROL , VOLUME , SHIPS , OPTIMIZATION , NAVAL VESSELS , RATES , EFFICIENCY , THESES , TRANSMITTANCE , FUELS , ENDURANCE(GENERAL) , BASE LINES , WEIGHT , MACHINES , ELECTRIC POWER , POWER , SHAFTS(MACHINE ELEMENTS) , GENERATORS , ELECTRIC GENERATORS , NAVAL ARCHITECTURE , MOTORS , ELECTRICAL EQUIPMENT , PERMANENT MAGNETS , ELECTRIC MOTORS , CONVERTERS , TRANSMISSIONS(MECHANICAL)


Subject Categories : Marine Engineering


Distribution Statement : APPROVED FOR PUBLIC RELEASE