13 kW High-Efficiency Six-Arm High-Gain Transformerless Floating Interleaved Bidirectional Buck–Boost DC–DC Converter for EV Applications

Abstract

A high-power-density bidirectional dc-dc converter, designated as the Advanced Six-Arm High-Gain Transformerless Floating Interleaved Bidirectional Buck-Boost dc-dc Converter, is described. This proposed converter offers low current and voltage ripple, reduced power losses, decreased stress on power components, and a reduction in magnetic volume. The short arms technique simplifies the structure and significantly enhances performance. Moreover, it does not require inductors proportional to the number of arms. The advantages are numerous, including switch command modulation. The ripple frequency of current and voltage at both ports is six times higher than the switching frequency, while the ripple frequency of current in the inductors is three times higher than the switching frequency. Additionally, there is a significant reduction in the volume and mass of passive components, balanced current distribution among the arms, and a remarkable capacity to achieve high power densities. The converter operates in open-loop mode, and this manuscript details the steady-state operating principle for the inductors’ continuous conduction mode. It presents parameter design guidelines, mathematical derivations, and a comparative analysis between the proposed converter and existing dc-dc converters. In addition, a 13-kW proof-of-concept laboratory prototype was designed, developed, and tested to validate the performance of the proposed converter across a wide range of load conditions. The measured efficiency is 97.96% at 54% of the power rating. Accompanying this manuscript is a video that demonstrates the converter’s operation.

Keywords

• Bidirectional dc–dc converter
• high power density
• transformerless floating interleaved converter
• ripple reduction
• high dc voltage gain
• electric vehicle (EV)