Internal Model based Current Control with Embedded Active Damping on a Three-Level PV Flying Capacitor Multilevel Inverter with LCL Filter

Multilevel converters are becoming favorable topologies to maximize the power transfer from solar panels to utility grids. As the harmonic emission of multilevel inverters are generally lower than their conventional two-level counterparts, not a bulky passive filter is required to eliminate the harmonic currents. However, the zero impedance of LCL filters at certain frequencies may expose the network to instability. In this paper, an embedded active damping technique based on virtual resistance method, within an internal model control scheme, has been implemented on a PV-flying capacitor multilevel inverter. An internal model of the LCL filter and the feeder line resistances are encapsulated in the controller and the difference between the control current output and the actual one passing through a compensator leads to the accurate control objective. Hardware-in-the-Loop case studies in Matlab/Simulink and Xilinx System Generator environment proves the robustness of the proposed control method.