Transformerless Grid-Connected Converters Using Active Virtual Ground Technique for Single-Phase Microgrids

Abstract

The paper presents the state-of-the-art technique Active Virtual Ground (AVG) in the design of single-phase grid-connected converters. The whole series of single-phase converters are based on the latest AVG technique. All of the designed topologies are with high efficiency, low leakage current, and single-stage structure. Focusing on the applications in ac microgrids, all of the evaluated topologies are classified into three different groups. They are associated with the three key components in the microgrid networks, which are power consumers, renewable energy sources and energy storage systems. The topology advantages and the design limitations of each converter type are analyzed in detail. The working principle of the AVG technique is demonstrated through the circuit equivalent model and is successfully verified in a set of 600 to 800 W prototypes. All of the experimental results are in good agreement with theoretical knowledge.