Phase shifted PWM with third harmonic injection for over-modulation range operation

Abstract

The paper presents novel Phase Shifted PWM method for multi-level inverters operated in the over-modulation range. The proposed method is based on combination of Generic Phase Shifted PWM method with third harmonic injection method. The first significant advantage of the proposed method over the conventional Phase Disposition (PD) PWM is equal power flow between the H-bridges and almost equal distribution of the switching operations number between them. Furthermore, it provides improved linearity in the over-modulation range. The proposed method is analyzed by extensive simulation results. Several aspects as Total Harmonic Distortion Factor of the inverter output currents, and voltages, harmonic content, frequency spectrum distribution and switchings number are studied.