Asymmetrical Duty-Cycle Limit Control-Based Multiport Bidirectional DC–DC Converter for Distributed Energy Storage System Applications

This article presents a novel multiport bidirectional dc–dc converter (MP-BDC) by featuring a two-phase interleaved architecture at each low-voltage port to mitigate current ripple across the low-voltage side capacitors and inductors. The multiport configuration is designed to enable the simultaneous utilization of energy storage systems (ESSs) with different voltage levels, while also achieving a wide voltage conversion ratio. In order to ensure the balanced average inductor current across the entire duty cycle range, a cost-effective asymmetric duty-cycle limit control strategy is implemented, which demonstrates the robust performance against variations in the dc inductors. Moreover, the proposed converter is well-suited for integrating various renewable energy resources and hybrid ESSs. In addition, the low-voltage ports are configured to share a common ground with the high-voltage port, which helps reduce electromagnetic interference within the system. The operating principles, device stresses, current ripple characteristics, and design procedures in the proposed MP-BDC are comprehensively analyzed. The essential performances are demonstrated by a 2.5 kW–50 kHz prototype with dual low-voltage dc ports (72 and 48 V) and a single high-voltage dc port (400–800 V) utilizing silicon carbide metal-oxide-field-effect-transistors (SiC-mosfets). The maximum efficiencies are measured as 98.04% with a high-voltage port of 400 V and 98.46% with a high-voltage port of 800 V, respectively. These results demonstrate the effectiveness of the proposed MP-BDC and highlight its potential for high-power applications, such as EV fast charging and renewable energy integration.