A Review on Multilevel Inverter: Topologies, Control Strategies and Application

Multilevel inverter is an attractive alternative for traditional two level inverter. It has many advantages over traditional multilevel inverter such as lesser voltage stress on switches, lesser filtering requirement and is free from electromagnetic interference EMI issues. It is being applied successfully in various medium power application such as AC power supplies, drive systems, and Distributed Energy Resources area (DER). In this paper, a review of multilevel inverter is addressed such as various traditional topologies, reduction of power switches,modulation, control strategies, and application. The control and modulation techniques such as Pulse Width Modulation (PWM) Techniques, space vector modulation (SVM) are described. Selective Harmonic Elimination (SHE) with mathematical modelling is addressed in detail. SHE-PWM is preferable as it operates at very low frequency and eliminate the lower order harmonics without any filtering circuit and reduction of switch count ensures higher efficiency with reduction of cost.