Peak-Zero-DPWM for Improving Performance of Single-Phase Five-Level T-Type NPC Inverter

The discontinuous pulse width modulation (DPWM) improves the efficiency and reliability of power devices by reducing the switching losses. However, it aggravates the Total Harmonic Distortion (THD) of outputs and the reliability of DC-link capacitors. Although DPWM enhances the reliability of power devices, from a system-level reliability perspective, the reliability of the single-phase five-level T-type NPC (5LT-NPC) can decrease due to the reduced reliability of the DC-link capacitors. In this paper, the impacts of the conventional DPWM and Z-DPWM defined in this paper on thermal loadings of the power devices and DC-link capacitors, output current THD, and power loss are comparatively analyzed. Based on the analysis result, the DPWM called peak-zero-DPWM (PZ-DPWM) is proposed. This method aims to address the limitations of conventional DPWM by improving the THD of the output currents and increasing the reliability of DC-link capacitors while maintaining the advantages of applying DPWM. Finally, the proposed DPWM is validated for its feasibility and effectiveness through simulation and experimental results.