A Symmetrical Transformerless Hybrid Converter with Leakage Current Suppression

Considering the high efficiency and flexibility, the transformerless hybrid converters with multiple outputs attract more and more attention in residential PV applications. However, the leakage current issue should be addressed properly to meet certain stringent safety regulations and standards. In this context, this paper presents a new symmetrical transformerless hybrid converter with simultaneous AC and DC outputs, while at the same time suppressing the leakage current. More specifically, a symmetrical boost-filter inductor is employed in the proposed converter to maintain a constant common mode voltage. The corresponding modulation methods with leakage current suppression for this converter are also proposed. Additionally, the derivation of the hybrid converter is summarized and one of its family topologies is presented as an example. Simulations are performed on a 3-kW hybrid converter system. The results have validated the performance of the proposed converter in terms of strong leakage current suppression, high power quality and also flexible reactive power injection.