Virtual Prototyping of MV & HV Modular Multilevel Power Converter using evolutionary Optimization based on ρ & η

The design of power electronics suitable for medium voltage (MV) and high voltage (HV) applications, such as the Modular Multilevel Converter (MMC), requires multi-disciplinary optimization of a very complex system consisting of many power electronic sub-modules, arm inductors and supporting structures, such as spacing for dielectric stand-off, mechanical frame and thermal management. A Virtual Prototyping Process (VPP) for systems made up of building blocks is proposed that executes an optimization routine capable of exploring a range of varying design space inputs while optimizing against competing objectives, such as power density (ρ) and efficiency(η). There has been high interest in developing ac-dc converters for MVdc and HVdc systems, FB-MMC (MMC with full bridge sub-modules) provide the compelling advantage of Power Electronic Converter based high speed dc fault protection, which is predominantly an important aspect in MVdc/HVdc transmission and distribution. Considering the importance of the topology and its growing popularity, this paper demonstrates how a design space that includes sub-module power electronic building blocks (PEBBs) with different voltage ratings, a range of power semiconductor devices, and varying MVdc bus voltage levels that can be optimally designed. The unique VPP takes into account practical system-building aspects such as dielectric voltage standoffs, creepage/clearance, accessible structures, modularized arrangement of building blocks, and electrical interconnects, all impacting the final design size and losses. The approach centers around ρ-η multi-objective optimization of the arm inductor, based on loss, mass and volume.