An Improved Four-Level Active Neutral Point Clamped Inverter With Relatively Uniform Loss Distribution

Recently, four-level inverters for low and medium voltage applications have been widely investigated thanks to their simple structure, low dv/dt, low switching loss, etc. However, the existing topologies have the disadvantage of unbalanced power loss distribution. For this reason, this article proposes an improved four-level active neutral point clamped inverter topology which is featured with low total voltage stress and uniform loss distribution under multiple operation conditions. These merits can fully utilize all power devices and expand the output capacity of the inverter. The operating principle and modulation strategy of this topology are described in detail and a comprehensive comparison with other four-level and three-level inverter topologies is analyzed. Finally, experimental results have been carried out to validate the proposed topology and its advantages in improving loss distribution.