Quasi-Reference PWM for 3-level Voltage Source Inverters

3-Level Voltage Source Inverters (3L-VSI) have emerged as effective approach to achieve high efficiency and better harmonic distortion performance. As a State-of-Art (SoA), two types of carrier arrangement methods are used for carrier-based pulse width modulation (PWM), namely, phase disposition (PD) and alternate phase opposite disposition (APOD). PD PWM gives better performance in terms of current quality and Total Harmonic Distortion (THD) whereas, APOD PWM is more effective for suppression of Common-Mode Voltage (CMV) with the expense of increased THD. In this paper, a novel Quasi-reference PWM method for 3L-VSIs is presented which results in low CMV as that of the APOD along with the reduced THD. The proposed method can be considered as a distinct trade-off between the two SoA methods, which maintains the merits of both. This paper presents the detail analysis and experimental verification of the proposed PWM technique.