A Current Control Method for an Interleaved Boost Converter Under CCM/DCM Operation in a PV System

DC-DC boost converters are widely adopted in power conditioning systems for renewable energy sources (RESs) and, due to unidirectional power transfer, are subject to operation in either continuous conduction mode (CCM) or discontinuous conduction mode (DCM). Current controllers that ensure operation in both modes have been developed, however, most of the solutions presented in the literature are developed for power-factor (PFC) correction rectifiers, limiting their application to other systems. In a two-stage photovoltaic (PV) generation system, the boost converter operates in a wide range of input voltages, resulting in DCM under low irradiance conditions or during system startup. This work presents an average current estimation method that provides similar performance to the current reference tracking regardless of the operation mode. The current controller has been designed based on the large signal averaged model which accounts for both operation modes. Moreover, a correction factor is derived to generate the correct duty cycle based on the average voltage of the switching leg. Simulation studies are conducted to evaluate the performance of the proposed method, the operation for the switching and averaged model is shown, and the transition between the two modes is demonstrated.