A Novel Active Neutral Point-Clamped Five-Level Inverter With Single-Stage-Integrated Dynamic Voltage Boosting Feature

Abstract

Application of mid-point-clamped multilevel inverters, e.g., active neutral point-clamped (ANPC) or stacked multicell (SMC) converters, have been significantly broadened in recent years due to better performance, reduced common-mode voltage and leakage current, bidirectional power flow capability and simplicity in circuit design. Nonetheless, the dc-link voltage utilization factor is only 50% (i.e., the peak of the ac output voltage is half of the dc-link voltage), which requires additional front-end boost integrated circuit to accommodate low and wide varying input voltage. In this article, a single-stage ANPC-based five-level (5 L) boost integrated inverter is proposed, which is able to meet the peak amplitude of the grid voltage even when the dc-link voltage is low and wide varying. The proposed topology is comprised of two boost inductors, four capacitors, and 10 power switches, which can be assembled with two standard T-Type modules and two additional discrete power switches. Compared with the conventional two-stage ANPC and/or SMC-5 L inverters with a front-end bidirectional boost converter, the proposed topology requires the same number of power switches, whilst providing more flexible/dynamic voltage conversion gain with a reduced total standing voltage across the switches. Operating principles, circuit analysis and modulation strategy of the proposed topology are discussed. Finally, a comparative study supported by closed-loop grid-tied experimental results are presented to confirm the potentiality and feasibility of this proposal.