Decentralized Control Strategy for Modular Three-phase Inverters with AC/DC Power Decoupling

In this paper, a quad active bridge converter for modular photovoltaic inverters is analyzed, which is able to realize the AC/DC power decoupling in the magnetic circuit without increasing the size of the transformer. Besides, a ripple-suppression control strategy is proposed to suppress the voltage ripples caused by the unavoidable parasitic circuit resistance and leakage inductance, so that the bus capacitance can be minimized. Meanwhile, on the basis of this modular structure, a decentralized control system architecture is presented to constitute a decentralized controller for the series-stacked system using the inherent synchronization and power-sharing capabilities of the coupled nonlinear oscillator. The effectiveness of the control strategy was verified through simulation and experiments.