Comparative study of different multilevel DC/DC converter topologies for second-life battery applications

This paper is part of a research project, which aims to investigate the possibilities of using the second life batteries after their replacement from plug-in electric vehicles (PHEVs), hybrid electric vehicles (HEVs) and battery electric vehicles (EVs) for smart grid applications. Batteries which are used for vehicular service cannot be used once that the capacity becomes less than 70%-80% [1]. The remaining capacity of the battery can be utilized for stationary applications during peak load hours and to reduce the environmental pollution. These batteries are defined as second life batteries. In these applications, the power electronic converters (PECs) play an important role in the development of high performance integrated systems. It means that the performance of the second life batteries mainly depends on the characteristics of the PECs, which are utilized to achieve the integration of the second life batteries with the smart grid. Therefore, this paper represents a comparative evaluation of different multilevel DC/DC converter topologies that can be used to connect the second life batteries to smart grid. Furthermore, the advantages and drawbacks of the most popular multilevel DC/DC converter (MLDC) topologies are presented in detail. In this paper, a selected harmonic elimination (SHE) technique has been used to realize the control system of the multilevel DC/DC converter, and its influence on the performance of each battery module is analyzed. These topologies are designed and verified by using MATLAB/Simulink environment.