Novel voltage space vector PWM algorithm of 3-phase 4-wire power conditioner

This paper proposes a novel voltage space vector PWM algorithm that is applied to the control of voltage source inverters (VSI) when they operate as 3-phase 4-wire active power conditioners. The idea is based on the concept of 3-dimensional voltage space vectors (VSV) in an αβ0 space. Under unbalanced conditions, the voltage switching state vectors are asymmetrical. A 3-dimensional voltage synthesis process can be carried out based on a normal VSV PWM method and splitting the zero vectors into different effective times, according to the 0 component. The new algorithm has been investigated thoroughly and can be implemented easily by the use of a digital-signal processor (DSP). The validity of the algorithm has been verified by the results of simulation. The proposed PWM strategy has the attractive feature that it can control 3 phases independently and flexibly in 4-wire systems