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

Yutian Lei, Christopher Barth, Shibin Qin, Wen Chuen Liu, Intae Moon, Andrew Stillwell, Derek Chou, Thomas Foulkes, Zichao Ye, Zitao Liao, Robert Carl Nikolai Pilawa Podgurski

Research output: Contribution to journalArticlepeer-review


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-V $ -{\text{DC}}$-To-240-V $-{\text{AC}}$ 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.

Original languageEnglish (US)
Article number7811253
Pages (from-to)8570-8581
Number of pages12
JournalIEEE Transactions on Power Electronics
Issue number11
StatePublished - Nov 2017


  • Active energy buffer
  • GaN
  • flying capacitor multilevel (FCML)
  • inverter
  • multilevel inverter
  • single phase

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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