Fuzzy based optimal switching angle-PWM controller for 27-level asymmetric multi-level inverter

Abstract

This work aims to improve the operation of multi-level inverter with reduced switching losses, thereby propose a new structure for an MLI with a reduced component count. A 27-level asymmetric Multi Level Inverter (MLI) with a minimal number of static switches is considered as a test system. The proposed MLI is developed with three input DC sources and thirteen power electronic switches. The hardware prototype is developed for 40 V and 3.5 A output. The control logic is developed in dsPIC30F410 controller. The main objective of this work is to effectively bring down the Total Harmonic Distortion (THD) of the resulting output voltage by analyzing the harmonic spectrum of the proposed MLI configuration with various low frequencies switching techniques and optimizing their switching angles and to choose an appropriate switching state using fuzzy logic controller (FLC). The proposed FLC covers wide range of operating conditions i.e. 10 switching states and variables 9*9 rules to predict the suitable switching angel. The performance metrics of the proposed structure of 27-level MLI has been evaluated upon simulation results and experimental results based on hardware prototype. The comparative study also carried out with the recent MLI topologies.