Model predictive control of a 3-phase grid-connected B6-inverter with LCL-filter in abc-coordinates

A MIMO1 current-control approach for 3-phase grid connected inverter systems in the abc-frame is proposed. Redundant states are eliminated and the system is controlled via an explicit MPC2-approach. To achieve steady-state accuracy, the system-model is augmented by a simplified grid-model to obtain a high dynamic control structure, which supersedes the use of resonant controllers and coordinate transformations. The developed control structure can handle balanced as well as unbalanced grid conditions without loss in accuracy and only consists of a single controller whithout any decoupling techniques. Furthermore, the property of MPC-schemes to explicitly respect state and input constraints facilitates the use of implicit flat-top alike modulation schemes to improve the efficiency for certain inverter topologies.