Buck converter-based cascaded asymmetrical multilevel inverter with reduced components

In this paper, a new topology of the cascaded asymmetrical multilevel inverter (CAMI) has been presented. In the output voltage of the CAMI, a high number of levels are required to reduce the total harmonic distortion (THD). To increase the number of levels, more auxiliary H-bridges are required to connect with the MAIN H-bridge of the CAMI, which increases the number of components, cost, and space for installation. To solve this problem, a low-rating buck converter is connected with one of the auxiliary bridge. With this modification, any number of levels can be achieved in the output voltage with lesser number of circuit components. To show the ability of the proposed variable voltage CAMI, it is compared with existing cascaded multilevel inverter topologies in terms of number of semiconductor devices, the number of DC sources, variety of DC sources, total standing voltage, the number of semiconductor devices in the current path, efficiency, and THD. In this paper, simulation of the proposed topology with nearest level control modulation has been performed using MATLAB/SIMULINK environment. The output voltage, load current, power factor, power, and THD have been obtained by simulation of 21-level variable voltage CAMI and are validated by experiment results under a resistive and motor load. Hardware implementation has been done by compiling nearest level control modulation into dSPACE DS1104 R&D controller board.