Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids

This paper proposes a five-level active-neutral-point-clamped (5L-ANPC) dc/dc converter for applications in medium-voltage dc grids. A modulation strategy is proposed for the 5L-ANPC dc/dc converter to generate multilevel voltage waveforms, which can effectively reduce voltage change rate dv/dt, reduce voltage stress on the transformer, and thus reduce the electromagnetic interference and increase reliability. An elimination method for the dead time effect is also proposed along with the proposed modulation strategy by employing a switch in series with the flying capacitor, which can effectively eliminate high voltage leaps caused by the dead time effect. In addition, a capacitor voltage control strategy is proposed for the 5L-ANPC dc/dc converter to ensure the balanced flying capacitor voltage and desired five-level voltage waveforms. Finally, simulation and experimental studies are conducted, and the results have verified the proposed converter and control strategies.