An Improved Current-Fed Bidirectional DC–DC Converter for Reconfigurable Split Battery in EVs

This article is aimed to propose an isolated current-fed bidirectional dc–dc converter (ICFBD
$^{2}$
C) in reconfigurable split battery (RSB) charging for electric vehicle applications. The proposed CFBD
$^{2}$
C is capable to counter potential issues of high-frequency CFBD
$^{2}$
C, such as high voltage spikes across switches, high initial input current, higher switch rating, hard-switched operation, narrow operating range, additional auxiliary circuitry, low charging current, and limited voltage gain. In this article, a CFBD
$^{2}$
C is proposed to charge RSB voltage sources. The proposed CFBD
$^{2}$
C comprises three stage gain circuit (synchronous boost converter, voltage doubler, and high frequency transformer) to match two dc voltage level. It operates in two distinguished modes of discharging and charging. In discharging mode, CFBD
$^{2}$
C offers an 8X voltage gain, and allows discharging of batteries to the grid. Furthermore, in charging mode, RSB is opted to the parallel configuration to inject high current due to high potential difference. In both operating modes, the proposed CFBD
$^{2}$
C ensures zero voltage switching turn
on
and zero current switching turn
on/off
for all the switches and diodes, respectively, during entire battery charging/discharging operation range. The theoretical analysis of the proposed converter is initially validated by SIMULINK9.0, and later on verified by a laboratory prototype of 250 W, validate 145 kHz for charging and 100 kHz for discharging with 94%.