Discontinuous Modulation for Improved Thermal Balance of Three-Level 1500-V Photovoltaic Inverters under Low-Voltage Ride-Through

This paper investigates the thermal behavior of a 90-kW/1500-V, three-level, neutral-point-clamped (3L-NPC), single-stage PV inverter during low-voltage ride-through (LVRT) operation. To improve thermal performance during LVRT operation, a modified discontinuous pulse-width modulation (DPWM) scheme is proposed in this paper. As a major outcome, we concluded that, with the proposed scheme, the thermal stress is distributed more equally among the power devices compared to that with the conventional strategy. Simulation and experimental results are presented to assess the effectiveness of the proposed DPWM.