MODELING AND CONTROL OF A MODULAR MULTILEVEL RECTIFIER

Medium-voltage direct current (MVDC) systems will be the backbone of power systems in the future naval fleet due to its numerous benefits compared with the existing medium-voltage alternating current (MVAC) systems. The rectifier is a key component in an MVDC system that converts the AC electrical power from ship generators to DC power for further transmission and distribution. The power density, efficiency, and power quality of the rectifier are critical to successfully implement an MVDC system. The goal of this thesis is to further improve the benefits of a new rectifier topology, the modular multilevel rectifier (MMR), by designing and implementing control system improvements. Using a real-time simulator, the MMR control system improvements were tested by simulating a system comprised of an MMR converting power from a 6.6 kV AC generator to a stable 12 kV DC bus. The various control improvements were tested against benchmark simulation results. This study shows that the control system improvements enhance the MMR power quality and reduce the number of required components making the MMR an ideal choice for naval MVDC systems.Lieutenant, United States NavyApproved for public release. Distribution is unlimited