An improved discontinuous modulation for three-level inverter

This paper proposes an optimized space vector modulation method for the switching loss reduction of the Neutral-Point-Clamped Three-Level Inverter (NPC-TLI). The main contributions are: 1) several different sequence patterns of the space vectors are compared and an optimized sequence pattern with low switching loss and low current THD is selected; 2) a new Discontinuous Pulse-Width-Modulation clamped to Zero (DPWMZ) is proposed for the switching loss reduction in low modulation ratio; 3) a fast detection method for the load power factor angle φ is designed with cle φ can be calculated in only one sampling period, and the no-switching duration is in the center of the peak value region of the load current. The loss can be reduced further. The simulation and experiment is presented to verify the concept proposed in the paper.