Reduced Switch Count Multilevel Inverters—A Review

Multilevel inverters are gaining much interest in recent days because of their high voltage and high-power handling capacity and improved power quality. Various multilevel inverters are reviewed in this paper by considering various parameters like number of switches, sources requirement, voltage stress on each switch, utilization factor of the switch, power losses etc. Different sinusoidal pulse width modulation (SPWM) control strategies are designed for each MLI. The output voltage and currents are observed with variable switching frequency and dynamic modulation index. Optimum control scheme with carrier frequency and modulation index are proposed. The proposed SPV system with five-level inverter is connected to the grid, and charge balance control is implemented through the proposed MLI topology with SPWM control scheme. Switched capacitor–based MLI topologies are compared with the isolated DC source–based MLI topologies, and high gain is possible with switched capacitor–based MLI topologies. Hardware prototype is developed for five-level MLI, and the experimental results are validated with the simulated results.