Design and construction of an isolated DC to DC switching converter for integration of energy storage systems in power electronic applications

Abstract

With the current trend towards greener energy sources, the integration of Energy Storage Systems (ESS) is the key to sustain the grid against fluctuations of energy generation. This raises a major concern for the inclusion of an efficient, fully controllable power conversion stage to allow an intermediate processing of energy flow. The Dual-Active-Bridge (DAB) converter provides full controllability as well as galvanic isolation. DC-DC Isolated conversion is a critical process in some applications such as Electric (EV) and Hybrid Electric Vehicles (HEV). Also linking ports up in a Multi-port DAB converter via multiport transformer allows for the integration of additional energy sources to the system. This converter can thus be employed in applications ranging from a front-end converter in points of common coupling at facilities, to a high power modular structure used on distribution system levels. The motivation behind the thesis is to study the Dual-Active-Bridge bidirectional dc-dc converter topology, and validate its operation for a 2kW rated power setup. A starting approach for the design procedure, covered in this work, is to employ the converter as a unidirectional power flow converter, supplying a load that resembles the behavior of a typical micro-grid, such as a resistance in parallel with a DC link. Thus, the operation of the converter at rated power can be analyzed, studied and optimized.