Application of improved firefly algorithm for programmed PWM in multilevel inverter with adjustable DC sources.

•Improved firefly algorithm is applied to determine the optimum switching angles for the 11-level cascaded H bridge multilevel inverter with non-equal DC sources.•Firefly algorithm takes least estimation time and surpasses all other 11 metaheuristic algorithms.•The algorithm and the model are developed using MATLAB and the validity of the simulation is confirmed by an experimental setup using FPGA Spartan 6A DSP.•Results are compared with the results obtained using Particle swarm optimization and artificial bee colony algorithm and it is proved that the proposed method offers reduced THD with less computation period.