A Multiport Current-Fed IIOS Dual-Half-Bridge Converter for Distributed Photovoltaic MVDC Integration System

The input-independent output-series (IIOS) dc–dc converter structure possesses the capability to achieve high voltage gain, single-stage power conversion, and multiport independent control, which is suitable for distributed photovoltaic (PV) power collection system. However, if the multiport input powers are different, the output voltage of each submodule (SM) will be uneven, which might lead to power degradation and device damage. In order to address SM output voltage imbalance problem, in this article, a voltage self-balancing output-series dual-half-bridge (OSDHB) converter based on multiwinding coupled inductor is developed. By multiplexing the SM secondary-side switches in OSDHB, the unbalanced power between SMs can be directly transmitted to the target SM, without the requisition for transmission one by one. And all power switches possess zero-voltage switching characteristic. Therefore, the proposed IIOS-DHB features high efficiency, low cost, simple control, and more adaptive to distributed PV power generation system. The topological configuration, operating principle, and self-balancing performance are presented. Finally, the full-scale simulations and three SMs down-scale experimental hardware platform have been conducted to verify the theoretical analysis of the proposed IIOS-DHB.