A Compact High-Power Noninverting Bidirectional Buck-Boost Chopper for Onboard Battery Energy Storage Systems

This article proposes a noninverting bidirectional buck-boost chopper accompanied by an auxiliary converter for battery storage that is installed in a light rail vehicle. The proposed chopper is composed of two half-bridge cells called the main converter, an auxiliary converter consisting of many full-bridge converters connected in cascade, and a small-sized inductor. It is controlled such that the capacitors of the auxiliary converter store and release most of the chopper energy instead of relying solely on a bulky and heavy inductor. As a result, it is lighter and smaller than the four-switch noninverting buck-boost chopper. The operation, as well as the control of the proposed chopper, are experimentally tested using a down-scaled prototype. Furthermore, a comparison with the four-switch noninverting buck-boost chopper with respect to mass, volume, and efficiency is made to verify the efficacy of the proposed chopper.