Five-Level Active-Neutral-Point-Clamped DC/DC Converter

Multi-level converters are getting more and more attentions because of their obvious merits such as lower voltage stress and harmonic, smaller size of output filters, and so on. In this paper, a five-level active-neutral-point-clamped (5L-ANPC) dc/dc converter is proposed for power transfer in the applications of the medium voltage dc (MVDC) grids. A modulation strategy is also proposed to achieve five-level voltages generating, which can effectively reduce the high voltage change rate dv/dt and voltage stress on the transformer, thus decrease the electromagnetic interference (EMI) and increase reliability. Furthermore, a capacitor voltage control strategy by alternating two operation modes of the proposed modulation strategy is proposed to balance the voltage of the flying capacitor, which ensures multi-level voltages producing. Finally, the performance of the proposed converter and control strategy is verified by both simulation results and experimental results from a down-scaled prototype.