A Bidirectional Nonisolated Multi-Input DC–DC Converter for Hybrid Energy Storage Systems in Electric Vehicles

TLDR

Hybrid energy systems require multi‑input DC‑DC converters that can transfer power from ESSs with varying voltage levels to a common output while minimizing component count. This work introduces a bidirectional, nonisolated multi‑input converter topology for electric‑vehicle hybrid storage systems that can accommodate ESSs with differing electrical characteristics. The proposed converter connects all inductors to a single switch, needs only one extra active switch per input, enables active power sharing, and its design was validated through simulation and a 1‑kW battery/ultracapacitor prototype.

Abstract

To process the power in hybrid energy systems using a reduced part count, researchers have proposed several multiinput dc-dc power converter topologies to transfer power from different input voltage sources to the output. This paper proposes a novel bidirectional nonisolated multi-input converter (MIC) topology for hybrid systems to be used in electric vehicles composed of energy storage systems (ESSs) with different electrical characteristics. The proposed converter has the ability to control the power of ESSs by allowing active power sharing. The voltage levels of utilized ESSs can be higher or lower than the output voltage. The inductors of the converter are connected to a single switch; therefore, the converter requires only one extra active switch for each input, unlike its counterparts, hence resulting in reduced element count. The proposed MIC topology is compared with its counterparts concerning various parameters. It is analyzed in detail, and then, this analysis is validated by simulation and through a 1-kW prototype based on a battery/ultracapacitor hybrid ESS.