A Modified Carrier-Based PWM Technique for Cascaded H-Bridge Inverters: Enhanced Harmonic Reduction and DC Bus Utilization

Multilevel inverters are a crucial component in renewable energy systems, motor drives, and grid system due to their capability to generate high-quality AC output power. Among various multilevel inverter topologies, Cascaded H-Bridge Multilevel Inverter (CHB-MLI) is known for its scalability and modularity. However, the main concern in CHB-MLI is the Total Harmonic Distortion (THD) caused by the switching algorithm that is not optimized, which can cause harm to the systems due to low power quality and efficiency. This paper addresses the issue of THD in CHB-MLI by proposing a modified Carrier-Based Pulse Width Modulation (CB-PWM) technique, namely the Third Harmonic Injection Square Pulse Width Modulation (THI2-PWM). The proposed method also aims to improve DC bus utilization. To validate the effectiveness of the THI2-PWM technique, simulations were carried out using MATLAB Simulink for a 5-level CHB-MLI system. The results demonstrate improved performance compared to conventional CB-PWM methods.