Integrated Multiport DC-DC and Multilevel Converters for Energy Sources

Abstract

This paper presents a novel converter system for integrating multiple renewable energy sources for both dc and ac grids. The proposed converter system is formed by integrating a novel multiport dc converter topology with a multilevel inverter topology, aiming to achieve multiple source integration with low component count and higher efficiency on the multiport converter section and efficient dc to ac conversion on the multilevel inverter section. As compared to counterparts in literature, where each energy source requires its own dc converter and the dc to ac conversion is achieved using a two-level converter, the converter system proposed in this paper has more attractive features of buck-boost operation, better power quality characteristics and low part counts. Within the framework, an auxiliary circuit-based dc link voltage balancing technique is proposed to balance the voltage on the dc link as compared to the more complex control-based balancing scheme. Open and closed loop operations of the converter system are numerically verified using simulations and validated by a high-fidelity hardware-in-the-loop implementation platform.