Transformer-less three-port grid-connected power converter for distribution power generation system with dual renewable energy sources

This study proposes a novel transformer-less three-port grid-connected power converter for a distribution power generation system with dual renewable energy sources. The proposed three-port power converter is configured by a three-leg bridge converter, a common-mode circuit and a filter inductor set. The proposed three-port power converter has a high-voltage DC port, a low-voltage DC port and an AC port. The high-voltage and low-voltage DC ports are connected to the dual renewable energy sources, a solar cell array as well as a fuel cell, and the AC port is connected to the utility. The proposed three-port power converter uses the concept of the differential-mode and the common-mode paths of electromagnetic interference filter. Consequently, the three-port power converter is controlled to generate a set of differential-mode currents and a set of common-mode currents. As a result, the differential-mode currents and common-mode currents pass through the differential-mode current path and the common-mode current path to perform the power conversion between the dual renewable energy sources and the utility. A prototype is developed and tested to verify the performance of the proposed three-port power converter. The experimental results show that the proposed three-port power converter achieves the expected performance.