Control strategy for a current-source boost-buck converter for PV systems

In this paper a two-stage grid-tied PV system is presented. The PV system consists on a first stage implemented by a DC-DC boost-buck converter, which has current source characteristics for both input and output, and a second stage implemented by a DC-AC converter tied to the grid, being a suitable choice for these applications. The mathematical model was obtained and validated for different operating conditions. Using the model, the transfer functions were calculated and used for designing the controllers of the topology. Simulation results of a 3.5 kW PV system are presented validating the control strategy, regardless the irradiation conditions avoiding undesirable behaviors of the input current and capacitor voltage. In addition, the results show total harmonic distortion, THD, below 5% and power factor equals to 1.