New direct regular-sampled pulse-width modulation applicable for grid and islanding operation of current source inverters

This study presents new direct regular-sampled pulse width modulation (DRSPWM) for grid connected three-phase current source inverters. The theoretical basis of the presented modulation strategy is described in detail and includes dwell time calculations and switching sequence selection. The modulation strategy is simple and suited for digital implementation, and has the flexibility and degree of freedoms of space vector modulation. This is because some switch sequences ensure a minimum number of switching transitions per fundamental cycle, unlike other methods presented in the literature. It is therefore applicable for high-power medium-voltage applications. The validity of the presented DRSPWM is confirmed using simulation and experimentation of a current source inverter, in open and closed-loop operations.