A New Seven-Level Active Boost Neutral Point Clamped (7L-ABNPC) Inverter

This paper presents a novel seven-level inverter circuit for a medium-voltage high-power applications. It consists of two inner flying-capacitor units forming a similar structure as of conventional T-type Active Neutral Point Clamped (ANPC) inverter. This unique arrangement and reduced number of both active and passive components with a simple modulation technique reduces both cost and complexity in the system design. This, in turn, will make the overall system appealing for various industrial applications (e.g. rolling mills, fans, pumps, marine appliances, mining, tractions, and most prominently grid-connected renewable energy, etc.). In addition, compared to conventional 7-Level Neutral Point Clamped (NPC), Active NPC (ANPC) and 7-Level Flying Capacitor (FC) family, the reduction of the dc-link voltage by 50% is a notable contribution. Hereafter, the inverter is named as Seven-Level Active Boost NPC inverter, or in short 7L-ABNPC inverter. The principle of operation and theoretical analysis supported by key simulation and experimental waveforms of a 2.2 kVA prototype are presented to prove the concept of the proposed 7L-ABNPC inverter.