HV Interleaved Multiphase DcDc Buck-Boost Converter

in electric vehicle (ev) systems, bi-directional dc-dc converters are used to interface the rechargeable energy storage system (ress) such as the battery bank with the high voltage dc-link of the inverter. currently multi-cell batteries used in automotive systems, such as ev or hev, are subject to a higher failure rate than single cell batteries. the more cells are used in series, the greater the opportunities to fail and the worse the reliability. when a cell has failed the entire string or even worse the battery must be replaced, which is extremely costly [1]. so, to have less cells in series increases the reliability of the system, which also leads to a lower voltage of the dc link. for this reason and many others, in a hybrid or electric vehicle powertrain, a boost dc-dc converter enables optimization of the battery system. this work aims to investigate all the benefits that come with interleaving technique in dc-dc converters for automotive systems. indeed, these kind of converters for use in high-performance and high-power applications have received increasing interest in recent years. in particular this research work, done with sevcon ltd focuses on the theory behind bi-directional multiphase interleaved (imc) converter and how it could be used to interface a rechargeable energy storage system (ress) to the powertrain of a hybrid or electric vehicle. more specifically, it was investigated if it is possible to use (after appropriate hardware and software amendments) a standard three phase ac motor inverter as a multiphase interleaved converter. for this purpose two motor controller, produced by sevcon have been analysed. both the gen4 size 10 and the hvlp inverters were considered for use as a dc-dc converter. the voltage can step up or down based on the power flow direction. each phase is indeed a bi-directional buck or boost converter, which is composed of a bridge of power switches and inductor.