Cylindrical coordinate control of three-dimensional PWM technique in three-phase four-wired trilevel inverter

In past decades, almost all the studies are focused in two-dimensional (2-D) PWM techniques on α-β frame. A four-legs inverter is proposed to compensate the three-phase four-wired system issues. However, three-legs center-split inverter can be applied to compensate the power quality issues including the zero-sequence compensation by the novel PWM technique: three-dimensional (3-D) PWM. In this paper, the mathematical model of shunt-connected three-level power inverter in three-phase four-wired system is studied in a-b-c-0 frame. The study of 3-D voltage space vector PWM technique in two-level and three-level inverters is performed in rectangular, cylindrical, and spherical coordinates, respectively. The 3DPWM performance indices are proposed. Comparative study of fixed switching sign cubical hysteresis control with this novel proposed technique "cylindrical coordinate control strategy" is accomplished. The results show that the performance of the proposed novel control strategy can overcome the drawbacks of fixed switching sign cubical hysteresis 3DPWM control strategy.