An Improved Simplified PWM for Three-Level Neutral Point Clamped Inverter Based on Two-Level Common-Mode Voltage Reduction PWM

In this article, a common-mode voltage reduction pulsewidth modulation (CMV-R PWM) for three-level neutral point clamped inverter based on the simplification of the three-level space-vector diagram into that of a two-level inverter is studied. By replacing the switching sequence of two-level space-vector PWM with that of CMV-R PWM, the common-mode voltage of the proposed method can be restricted to one-sixth of the dc-link voltage. With the new switching sequences, the neutral-point voltage control by calculating an optimized injected zero-sequence voltage is introduced. Simulation and comparative analysis is given to illustrate the features of the proposed method. The effectiveness and correctness of the proposed method is verified by experiment.