MPC Control of Three-Phase CSI in Unbalanced Grid

With the benefit of saving a stage of DC/DC converter and the electrolytic capacitors on the DC side of the inverter, the current source inverter (CSI) is attracting the focus as the interface between the PV power panel and the grid in recent years. This paper proposes a continuous control set-model predictive control (CCS-MPC) for a three-phase CSI in an unbalanced grid. In the proposed strategy, the current reference is calculated according to the power reference and grid voltage. Then the CCS-MPC is designed to track the current reference. To damp the oscillation of the filter, both inductor current and capacitor voltage are introduced into the cost function. The desired current vector is calculated by minimizing the cost function and is achieved by SVPWM. The proposed strategy enables the fast response of CSI without oscillation in both balanced and unbalanced grids. The effectiveness of the proposed strategy is verified by simulation results.