A simplified predictive current Controlled Cascaded H-Bridge Multilevel Inverter for grid-connected photovoltaic systems

In this paper, a single phase Predictive Current Control (PCC) method has been implemented and simulated for Cascaded H-Bridge (CHB) Multilevel Inverter that is used in grid-connected photovoltaic systems. The multilevel converter consists of several H-Bridge cells being connected in series. Each H-Bridge Cell is fed by a DC/DC converter as a dc voltage source and the multilevel inverter is applied to convert DC power to AC power and deliver it to the grid. Two alternative control implementations have been introduced and simulated. The proposed control method is capable of controlling the multilevel inverter in either symmetrical or asymmetrical dc voltage source condition. Predictive Current is calculated on the basis of the possible values of voltage and then the switching state that makes the nearest predictive current to the reference current is selected. Low ripple sinusoidal-waveform current is generated with arbitrary power factor. Simulation has been carried out and the results of simulation for both alternative control implementations has been shown and compared. The comparison has been done, considering Harmonic Performance in current and voltage, and reference current tracking ability.