Asymmetrical Multilevel Inverter Topology with Different Sine Pulse Width Modulation Techniques

Multilevel Inverters (MLI) have gained widespread acceptance for renewable energy applications like wind and PV solar, etc., due to their suitability for distributed generation. The topology presented can produce a 5-level voltage output in a symmetrical configuration (i.e., $V_{d c l}=V_{d c 2}$) whereas 7 and 9-level voltage output in an asymmetrical configuration. This article presents a reliable nine-level asymmetrical MLI topology, comprising level and polarity generation units with an input DC source ratio of 3:1. Compared to classical topologies, the presented configuration incorporates a lower count of DC sources, semiconductor switches, capacitors, diodes, etc., The MLI is assessed using various Sine Pulse Width Modulation (SPWM) control techniques, including Level Shift PWM (LSPWM), Phase Shift PWM (PSPWM), Nearest Level Control (NLC), Hybrid Fundamental Switching Frequency Optimal (SFO) control PWM, and single carrier PWM. A comparative analysis of these modulation techniques with the proposed MLI is performed based on THD analysis of output voltage and current. The simulation of the proposed 9level asymmetrical MLI, along with various PWM control methods, is carried out using MATLAB/Simulink software.