Optimal sizing of modular multi-level converters designed for shipboard applications

Abstract

With the push towards Medium Voltage DC (MVDC) based shipboard electrical distribution systems, the power converter(s) between Medium Voltage AC generators and common MVDC buses must handle more power than any other electrical power conversion component in the ship. The Modular Multi-Level Converter (MMLC) is a compelling topology for this function because of its modular structure and the potential for achieving economies of scale and, hence, lower cost power conversion equipment. It is vital to consider the optimal sizing of all capacitive and magnetic storage elements within the MMLC in order to achieve the highest power density and determine its feasibility in the shipboard context. This paper presents an optimization process that is applied to the MMLC to achieve the highest power density given a set of requirements, environmental constraints, such as available cooling system attributes and technology insertions, such as Wide Band Gap (WBG) power semiconductors.