Analysis and design of single-stage, two-mode AC/DC converters for on-board battery charging applications

On-board battery chargers (OBCs) offer the feasibility of charging electric vehicles or plug-in hybrid electric vehicles with a standard household power supply. In this study, an OBC using two-mode topology (step-up or step-down) is presented. One of the main concern with two-mode topologies is the hard transitions of the converter operating from boost mode to buck mode or vice versa, which can deteriorate the performance of converter. This study provides smooth transitions between the modes and can have an output that could be more or less than the peak of input voltage. The detailed analysis of operating modes involved in the converter are analysed in the study. Moreover, the stress analysis on the components is also detailed in this study and the results are compared with existing two-mode converters. A simple dual-loop control structure with the proposed modulation technique eliminates the sub-harmonic oscillations and stabilizes the output voltage is also presented in the study. Experimental validation is performed for a 1.0 kW laboratory prototype and the results obtained are detailed in the study. This proposed converter topology can be applied as a single-stage OBC or as a power factor correction converter with variable DC link voltages in isolated two-stage OBC.