Simulation and implementation of FPGA based hybrid asymmetric multilevel inverter

Abstract

This work focuses on proposing a new structure for asymmetric multilevel inverter. In the proposed topology, a switched capacitor (SC) and conventional series inverter are combined and connected in cascade. The proposed multilevel inverter finds its application in photovoltaic inverters which has numerous advantages. Firstly, it converts power for AC requirements from comparatively low DC voltage sources and with lower number of switching devices. Second, with the removal of transformers normally used for stepping up the voltage of each inverter stage the weight, volume and size of the whole system is reduced as the proposed topology can double the input voltage without a transformer. Symmetrical step control method (SSCM) and fundamental switching frequency method (FSFM) are applied to this proposed topology to actuate the power electronic switches for effective control and monitoring of voltage levels generated at the output. The simulation is executed using MATLAB/SIMULINK software. It was found that FSFM modulation technique results in a lower value of Total Harmonic Distortion (THD). The switching strategy is implemented with an FPGA device for the experimental prototype. The simulation and experimental result of single-phase 25-level inverter is given to demonstrate the precise operation of the suggested topology.