Three-phase three-level flying capacitor converter with only one capacitor

This paper introduces a novel three-phase, three-level flying capacitor converter (FCC) that uniquely utilizes only one capacitor, addressing the power density limitations of conventional FCC designs that require multiple capacitors. To further enhance performance, a novel modulation strategy with predictive capacitor-voltage control is proposed, ensuring precise output-voltage regulation and a stable capacitor voltage at half of the DC voltage. A detailed comparison of the component counts, power losses, and voltage stresses with conventional three-level converters is provided to highlight the advantages of the proposed system. Experimental validation is carried out on a 500-W prototype, demonstrating a significant reduction in the capacitor count, along with outstanding steady-state performance, high power-conversion efficiency, and a fast dynamic response. These attributes make the proposed FCC highly advantageous for applications with stringent size, cost, and reliability requirements, such as electric vehicles.