Modeling and Control of a Three-Phase Five-Port Partially Isolated DC–DC Converter for DC-Powered Commercial Buildings

This is the authors' abstract. We don't add key points for this paper.

Integrating low-voltage, high-power energy sources and energy storage devices into medium voltage (e.g., <tex-math notation="LaTeX">380\ V</tex-math>) DC microgrids presents significant challenges due to the need for high-current and high-gain power conversion. This paper proposes a five-port, partially-isolated DC-DC converter to efficiently interface solar PV, battery, fuel cell, and supercapacitor with a <tex-math notation="LaTeX">380\ V</tex-math> DC bus. At the core of the proposed topology is a current-fed asymmetrical three-phase triple active bridge (A-TAB) structure, which results in a higher-order system, making its modeling and controller design challenging. To address this, a simplified small-signal modeling approach and a proportional-integral (PI) controller-based control scheme are proposed, enabling seamless operation of the converter under any energy management scheme (EMS). Further, a limiter-based novel autonomous power adjustment strategy is introduced to manage substantial load/PV power variations between consecutive EMS updates. The topology reduces power conversion stages, requires <tex-math notation="LaTeX">4%</tex-math> fewer semiconductor switches, uses <tex-math notation="LaTeX">20%</tex-math> fewer magnetic cores per phase and port compered to existing equivalent fully-isolated and partially-isolated converters. It also lowers the load bus voltage undershoot/overshoot by almost 10 times for the same percentage of load change. The experimental validation on a <tex-math notation="LaTeX">2\ kW</tex-math> laboratory-scale prototype confirms the effectiveness of the control strategy and overall system performance.