A 2-kW Single-Phase Seven-Level Flying Capacitor Multilevel Inverter With an Active Energy Buffer

• Published in: IEEE transactions on power electronics Vol. 32; no. 11; pp. 8570 - 8581
• Main Authors: Yutian Lei, Barth, Christopher, Shibin Qin, Wen-Chuen Liu, Intae Moon, Stillwell, Andrew, Chou, Derek, Foulkes, Thomas, Zichao Ye, Zitao Liao, Pilawa-Podgurski, Robert C. N.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Active energy buffer; Buffers; Capacitors; Charging; Converters; Decoupling; Density measurement; Efficiency; Electronic equipment; Energy conversion efficiency; Energy harvesting; flying capacitor multilevel (FCML); GaN; Inductors; inverter; Inverters; multilevel inverter; Power system measurements; single phase; Solar energy; Specifications; Switches; Switching frequency
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2017.2650140

High-efficiency and compact single-phase inverters are desirable in many applications such as solar energy harvesting and electric vehicle chargers. This paper presents a 2-kW, 60-Hz, 450-VDC-to-240-VAC power inverter, designed and tested subject to the specifications of the Google/IEEE Little Box Challenge. The inverter features a seven-level flying capacitor multilevel converter, with low-voltage GaN switches operating at 120 kHz. The inverter also includes an active buffer for twice-line-frequency power pulsation decoupling, which reduces the required capacitance by a factor of 8 compared to conventional passive decoupling capacitors, while maintaining an efficiency above 99%. The inverter prototype is a self-contained box that achieves a high power density of 216 W/in 3 and a peak overall efficiency of 97.6%, while meeting the constraints including input current ripple, load transient, thermal, and FCC Class B EMC specifications.