An Improved Current-Fed Bidirectional DC–DC Converter for Reconfigurable Split Battery in EVs
Pavan Singh Tomar, Manaswi Srivastava, Arun Kumar Verma
Abstract
This article is aimed to propose an isolated current-fed bidirectional dc–dc converter (ICFBD <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> C) in reconfigurable split battery (RSB) charging for electric vehicle applications. The proposed CFBD <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> C is capable to counter potential issues of high-frequency CFBD <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> C is proposed to charge RSB voltage sources. The proposed CFBD <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> C ensures zero voltage switching turn <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and zero current switching turn <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on/off</small> 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%.