A comprehensive study of relationship of two simplified space vector modulation methods and the application in three-level inverters

In this paper, two modified space vector pulse width modulation (SVPWM) methods are presented. The relationship of them is comprehensively studied. A variable factor ko is introduced into the unified voltage modulation method. Due to factor ko, the time duration of application of two zero state vectors is made changeable from 0 to 100% over the sampling period for their combined application, which makes the strategy is flexible and universal. Additionally, by introducing factor ko into the unified voltage modulation, it can prove that the two simplified SVPWM schemes are exactly identical. Owing to the variable factor, the two simplified SVPWM methods can be employed to balance the neutral-point potential in the neutral-point-clamped three-level inverter. The proposed modulation technique is verified by experiment.