FPGA implementation of generalized modulation for hybrid multilevel inverter with fixed ratio DC link voltage

In this paper, an FPGA implementation of generalized modulation for hybrid multilevel inverter, having fixed ratio dc voltage for each cell, has been proposed. A hybrid inverter consists of number of high voltage H-bridge cells, each operating at the fundamental frequency and a low voltage PWM operated H-bridge cell. The proposed modulation algorithm is independent of the actual dc link voltage of the cells. Also the templates for output voltage of each high voltage cells are generated internally without any need of inverter output voltage feedback for comparison with the reference. Verification of the proposed modulation algorithm is obtained for a seven level hybrid inverter using two cascaded H-bridge cells, both through the simulations and experiments. In experimental verification, the modulation algorithm is implemented using LabVIEW FPGA module programming on reconfigurable data acquisition board.