An Evaluation of electric motors for ship propulsion

An evaluation was conducted of the various propulsion motors being considered for electric ship propulsion. The benefit of such an evaluation is that all of the propulsion options being considered by the U.S. Navy have been described in one document. The AC induction motor, AC synchronous motor, High Temperature Superconducting (HTS) motor and Superconducting DC Homopolar Motor (SDCHM) are examined. The properties, advantages, and disadvantages of each motor are discussed and compared. The power converters used to control large propulsion motors are also discussed. The Navy’s IPS program is discussed and the results of concept testing are presented. Podded propulsion is introduced and the benefits are discussed. The final chapter presents the simulation results of a volts/Hertz controlled 30 MW induction motor. The evaluation revealed that the permanent magnet motor is the best propulsion motor when considering mature technology, power density, and acoustic performance. HTS motors offer significant volume reductions and improved acoustic performance as compared to conventional motors. This includes both AC and DC HTS motors. The main obstacle for the SDCHM remains the unavailability of high current capacity brushes.