Cascaded H-bridge converter with multiphase isolated DC/DC converter for large-scale PV system

The large-scale grid-connected photovoltaic (PV) systems have continuously increased, reaching hundreds of megawatts level. This trend will continue in the upcoming years, thus rising new challenges to the existing PV system configurations and grid converters design. The cascaded H-bridge (CHB) converter could be a possible solution to these challenges in terms of scalability and modularity. However, the CHB converter topology faces the issue of leakage current which could cause safety issues. Moreover, the inherent power imbalance issue of a PV system using a CHB topology needs to be handled. This paper introduces a multiphase isolated DC/DC converter which eliminates the leakage current issue. Additionally, a control strategy has been implemented to deal with the power imbalance between different H-bridges in one leg and also between the three phases. Simulation results are presented to validate the performance of the proposed PV system configuration.