Modulated Predictive Current Control of Photovoltaic Central NPC Inverter With Reduced Computational Burden

This paper proposes a computationally efficient modulated model predictive current control method for a three-phase neutral-point clamped (NPC) central inverter in the photovoltaic energy system. The proposed control method produces optimal triangular region consisting of optimal voltage vectors through an optimization function analysis. The optimal voltage vectors along with their duty cycles are used in the modulation stage to accomplish constant switching frequency operation, low steady-state errors and fast transient response. The control method accomplishes the system requirements such as the maximum power point tracking, balancing of the DC-link capacitor voltages, grid reactive power control, and grid synchronization. The proposed method is evaluated with a MATLAB/Simulink simulation on an 817 kW system under steady-state and varying solar irradiance conditions. The experimental validation is accomplished with a dSPACE MicroLabBox for a 5 kW system to validate the simulation results.