A Compact Envelope-Type Module for Asymmetric Multilevel Inverter with Reduced Components and PSO-Based Selective Harmonic Elimination

This paper introduces a design of a compact envelope-type (E-type) module which simplifies the construction of asymmetric multilevel inverters (MLIs) by using significantly lesser number of switches in a three-phase system. There are eight switches in each E-type module out of which two are bidirectional in addition to four unequal DC voltages to create thirteen distinct voltage levels. Main advantages of the proposed module include its internal polarity generation, reducing number of H-bridge used hence reducing the voltage stress on devices. To get more accurate output, we use Particle Swarm Optimization (PS0)-based Selective Harmonic Elimination (SHE) strategy for selecting the switching angles. This makes sure that the selected harmonics are eliminated and thus the Total Harmonic Distortion is reduced (THD). This proposed module design also allows cascading of multiple modules thereby increasing voltage levels and improving system flexibility. The Simulink-based results that have been derived prove that the proposed module is effective, demonstrating the output for a 13-level inverter with reduced THD. Moreover, loss analysis is also performed to showcase the usefulness of proposed module due to reduced switching. The E-type inverter that has been proposed boasts of its compact design, enhanced harmonic reduction and modular stability which allows it to provide solutions for both medium- and high-voltage power conversion as well as renewable energy applications.