IEEE Access (Jan 2024)
Performance Enhancement and Addressing Cross-Regulation in MIMO DC-DC Converters for Electric Vehicles
Abstract
Electric vehicle chargers are categorized into high-voltage DC (HVDC) systems for charging power batteries and low-voltage DC (LVDC) systems for low-voltage batteries. As next-generation EVs evolve, the demand for chargers with higher power ratings, greater power density, and lower losses, complicates system design. The rising load requirements necessitate a compact, lightweight, and efficient design, highlighting the importance of effective EV design for both industry and academia. This research presents a novel examination of Dual-Input Dual-Output DC-DC Boost, Buck, and Buck-Boost Converters, which are intended to transform a DC voltage input into several DC output voltage levels suitable for EVs. Current multi-port converters often encounter challenges such as limitations on duty ratios, inductor charging currents, output voltage restrictions, and cross-regulation problems during load fluctuations. This study introduces a multi-port DC-DC converter with Multi-Input Multi-Output (MIMO) capabilities that overcome these challenges, allowing for two distinct output voltages without restrictions on duty cycles or inductor currents. The proposed design resolves cross-regulation issues, ensuring that the output voltages V01 and V02 are stable and unaffected by changes in output currents i02 and i01. The outputs operate independently without influencing each other during use, and the loads are kept isolated during control processes. In this paper, the operating principle of the proposed converter is analyzed with the small-signal model, the average model of the converter is derived, and the transfer function of the proposed converter is further obtained. To ensure the response speed and stability of the converter, the voltage and current for closed-loop control are adopted, with which classical PI regulators are utilized and designed. The effectiveness of the proposed converter has been validated through a 1kW and 500W prototype, which successfully provides two output voltages of 150V and 30V, with the potential for additional outputs.
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