Asymmetric control algorithm for non-isolated type on-board battery charger with single controller

A non-isolated single-stage on-board charger (OBC) for electric vehicles (EVs) has been proposed in order to satisfy high efficiency and high power density. However, the conventional works could not achieve high efficiency according to the voltage variation of the utility and the battery, especially during the step-down operation. This paper proposes an advanced control algorithm to improve the system efficiency under the step-down mode by controlling each switch of the OBC asymmetrically. Moreover, the proposed algorithm consists of only one controller, which eliminates a transient state from variation of the controller. From the decreased the magnitude and the ripple of the inductor current, the charging efficiency is improved about 3.5% from the conventional algorithm under the step-down mode.