Hybrid PWM on the basis of SVPWM and SHEPWM for VSI as part of 3L-BtB-NPC converter

Abstract

The purpose of the research is to develop and study Hybrid PWM for three level back-to-back neutral-point clamped converter (3L-BtB-NPC) based on active front-end rectifier and voltage source inverter. Hybrid PWM must provide smooth switching between the algorithms of space vector PWM and selective harmonic elimination PWM of VSI. This allows to decrease the losses in VSI, which arise when commutating under SVPWM, by decreasing the number of switches under SHEPWM. To achieve the purpose, the mathematical model of 3L-BtB-NPC converter based on AFE rectifier and VSI under SVPWM and SHEPWM was developed. Applying a developed simulation model in Matlab/Simulink, the power quality of VSI under SVPWM and SHEPWM was evaluated. Based on theoretical and experimental research, it was proved that applying Hybrid PWM with transition SVPWM on switching frequency 300 Hz and SHEPWM with eliminating 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35 and 37 harmonics decreases the amount of semiconductor modules switches of VSI by 56.7% under identical THD of current and voltage.