A Three-Phase Five-Level Inverter With High DC Voltage Utilization and Self-Balancing Capacity of Floating Capacitor

Multilevel inverter are popular solutions in photovoltaic power station, wind farm, and other renewable energy generation. This article presents a three-phase five-level inverter with high dc voltage utilization. A significant feature of the inverter is that its maximum dc voltage utilization is twice that of the traditional three-phase inverters such as neutral point clamped, flying capacitor (FC), cascaded H-bridge, and active NPC. What is more, the inverter can realize the self-starting and self-balancing of the FC, and the self-balancing of the dc-link capacitors, so the complex FC voltage balancing strategy and bus midpoint voltage control method are not needed anymore. The voltage and current stresses analysis and the design guidelines of components are discussed in detail. A comparison with some existing topologies has also been made to highlight its performance. Taking one phase as an example, both the simulations and experiments are carried out to verify the validity of the proposed inverter and modulation strategy.