Implementation of cascaded asymmetrical multilevel inverter for renewable energy integration

This paper aims to develop a new cascaded asymmetrical multilevel inverter with less number of switches for photovoltaic power generation. The structure contains three sources and 11 switches. A design of proposed structure is suggested for PV application. A few more algorithms for cascade extension are also proposed to obtained maximum voltage levels using least numbers of switching devices. PD LS-PWM modulation is used to control gate pulses of the switches. The structure produce 15 levels using one inverter, whereas 85 levels using a cascaded inverter. The magnitude of sources in cascade inverter is governed by algorithms. A comparative assessment for optimal algorithm is developed considering, sources, switches, and other performance parameters. The simulation and hardware is performed for 15-level and 85-level asymmetrical inverter for variation in modulation index and frequency. The efficiency of multilevel inverter is evaluated using PSIM tool. The performance indices, power loss analysis, switching stresses, and blocking voltages across the switches are simulated and validated. The cascade structure, 85 levels produce high quality waveform, for which THD is less than 5%. Thus, this structure suits series combination of various PV panels and achieve power utilising renewable energy sources.