A Flexible Hybrid Selective Harmonic Elimination Transition Algorithm to Provide Variable Frequency of Output Voltage in 3L-NPC Inverter

Abstract

A versatile hybrid pulse width modulation (HPWM) scheme, which can combine individual characteristics of diverse PWM techniques and provide variable frequency of output voltage, is proposed for three-level neutral point clamped (3L-NPC) inverter based on change in pattern signal. In the presented HPWM, various switching patterns of selective harmonic elimination pulse width modulation (SHEPWM) are applied to adapt to each changed pattern, which varies according to the changed frequency. Moreover, one fast and smooth transition strategy is also investigated between these SHEPWM switching patterns, considering the aspects of reliability, efficiency and safety of the switched system. Finally the simulation results acquired through MATLAB/SIMULINK platform are used to validate and evaluate the feasibility and performance of the whole control system.