Cascaded Z-source Inverter Control Based on Bidirectional Positive and Negative Sequence Decoupling

Cascading technology attracts attention for its advantages of adapting to high-power, high-voltage power electronic converters. Various cascaded topologies and related control techniques have been proposed. This paper focuses on the cascaded three-phase Quasi-Z source photovoltaic (PV) inverter, which consists of a ZSI module and a line voltage cascade mode. The ZSI module includes a photovoltaic panel, a Quasi-Z source network and a three-phase inverter. When the transmission power is unbalanced, the characteristics of the inverter are analyzed, and the corresponding mathematical model is established. According to the characteristics of bidirectional energy transfer between ZSI modules, a bidirectional positive and negative sequence decoupling control algorithm is proposed, which can realize DC side voltage-sharing and suppress negative sequence component. The effectiveness of the control algorithms is verified by simulation results.