Rapid Prototyping of FPGA Controlled Common Ground Single-Phase Transformerless Five-Level Inverter using Xilinx System Generator

This paper presents a Field Programmable Gate Array (FPGA) implementation for rapid prototyping of a new single-phase transformerless five-level inverter for PV applications. The inverter features a reduced device count, a common ground that eliminates the leakage current issue, and 100% DC utilization. It is capable of supplying both real and reactive power. A simple proportional-resonant (PR) controller is developed and uses a level-shifted pulse width modulation scheme to generate the firing pulses. Grid synchronization is achieved using a robust arc-tangent method-based phase-locked loop (PLL) strategy. To evaluate the open-loop performance, an experimental prototype is developed, and its responses are presented. Moreover, a hardware-in-the-loop (HIL) co-simulation is performed for grid interface to achieve real-time constraints on an Atlys Spartan 6 FPGA using Xilinx System Generator in the MATLAB/Simulink environment, and the results are reported. Finally, a detailed comparison of various five-level inverter topologies is presented to highlight the merits of the proposed topology.