Current-Fed Isolated Three-Phase Matrix-Type Grid Inverter With Soft-Switching Capability.

The grid inverters play an important role in renewable energy systems, transferring the dc power to the ac grid. Galvanic isolation is usually needed between the dc source and the grid due to safety reasons and grounding leakage current mitigation. In this article, a soft-switching isolated grid inverter is proposed based on the current-fed matrix-type configuration. The topology of this converter is composed of a current-fed H-bridge on the side of dc source and a direct matrix converter on the grid side, which are linked by a high-frequency transformer. The current-fed H-bridge on the primary-side can smooth the dc-source current and control the dc-source current directly. The avoidance of dc-link energy-storage element in the single-stage matrix converter can prolong the system's life. A space-vector-modulation-based soft-switching scheme is proposed for the matrix converter on the grid side and a model-based commutation method is adopted in the current-fed H-bridge on the dc side. With the proposed modulation methods, the soft switching can be realized for all devices in the converter. Finally, a laboratory prototype of the proposed converter has been built to verify the effectiveness of the proposed method experimentally. [ABSTRACT FROM AUTHOR]