Novel converters for electric ship propulsion system and shipboard power distribution

This paper presents a novel propulsion system concept with numerous advantages. The heart of the concept is a motor drive and control topology we call "pulse frequency modulation (PFM)" The PFM concept is a fundamentally different method of distributing and converting electrical power that is well suited for any motor type and power distribution topology, including permanent magnet motors (PM). Many benefits accrue from using PFM topologies in future ship designs. Three of those benefits are particularly important to reconfigurable electric ship design: (1) very high power density (a minimum factor-of-five increase); (2) very low harmonic distortion (less than one percent); and (3) reconfigurable electric ship compatibility. Compatibility with the reconfigurable electric ship stems from the fact that by using the PFM topology, power system designers have flexibility never before available. With minor hardware variations, the system designer is able to change AC frequencies, to connect AC to DC easily, to convert both AC and DC voltages up or down, to inject out-of-phase harmonics to compensate for slot noise, to provide uninterruptable power, to handle PM motor faults efficiently, to provide full four-quadrant operation, to provide programmable interconnects between the ship\´s service zones and the propulsion modules, and to level loads throughout the system.