Generators for use in electric marine ship propulsion systems

Ship propulsion using electric drives is a quickly evolving technology. Industry focus to date has been on the most unique parts of the system, the electronic motor drives and propulsion motors. The input power presumed for these systems is typically conventional AC power. Additional benefits can be obtained by removing the constraint of conventional AC input power. System performance and arrangement advantages using generators with higher frequency, higher speed, higher phase number and close-coupled rectifiers are described. Emerging electronic motor drives having high quality power output are based on Pulse Width Modulated (PWM) architectures and multi-level PWM architectures for higher voltage systems. Significant improvements in system size, weight and efficiency can result by designing the generators for these state-of-the art systems with characteristics and features that optimize the overall system. Various generator designs are presented that illustrate the system impact of high speed, high frequency, high-quality DC output and multi-phase group generator architectures.