Phase Disposition PWM (PD-PWM) Technique to Minimize WTHD from a Three-Phase NPC Multilevel Voltage Source Inverter

Neutral-point clamped multilevel inverter (NPC- MLI) has become a widely accepted choice in the area of industrial drive applications. The problem concerning the higher harmonic content and the higher switching frequency still exist in the conventional NPC-MLI topology. In this paper, a phase disposition pulse width modulation (PD-PWM) technique is proposed for a three-phase five-level NPC-MLI, which is proficient in reducing the high-frequency weighted total harmonic distortion (WTHD) content of the inverter output voltage by employing a mathematically formulated harmonic mitigation algorithm. The experimental results of a three-phase NPC-MLI prototype hold a good resemblance with the theoretical calculation and simulated results of the proposed control scheme. Besides, a quantitative comparative investigation affirms that the proposed PD-PWM technique exhibits the lowest WTHD content among all the earlier- proposed PWM schemes under study, which verifies the preeminence of the proposed work.