A 6-level Flying Capacitor Multi-level Converter for Single Phase Buck-type Power Factor Correction

This work investigates behavior of flying capacitor multi-level (FCML) converters in single phase buck-type power factor correction (PFC) applications. Recent developments in FCML converters using GaN transistors are leveraged to improve power density of a single-phase 240 VRMS ac to direct 48 V dc conversion stage in data center power delivery applications. Here, we experimentally demonstrate this concept by using a digitally controlled 6-level FCML converter. The experimental prototype achieves 163 W/in3 by box volume excluding heat sink and twice-line frequency energy buffer. A key contribution of this work is experimental exploration of flying capacitor natural balancing of an FCML buck converter in a single-phase ac-dc conversion where the flying capacitor voltages must swing at 120 Hz.

[1]  Robert C. N. Pilawa-Podgurski,et al.  Design and implementation of a 1.3 kW, 7-level flying capacitor multilevel AC-DC converter with power factor correction , 2017, 2017 IEEE Applied Power Electronics Conference and Exposition (APEC).

[2]  T.A. Meynard,et al.  Natural Balance of Multicell Converters: The General Case , 2006, IEEE Transactions on Power Electronics.

[3]  S. Pirog,et al.  Selection of parameters for balancing circuit of DC-DC and AC-AC multicell converters , 2005, 2005 European Conference on Power Electronics and Applications.

[4]  Tomas Modeer,et al.  Experimental evaluation of a 1 kW, single-phase, 3-level gallium nitride inverter in extreme cold environment , 2017, 2017 IEEE Applied Power Electronics Conference and Exposition (APEC).

[5]  Zitao Liao,et al.  A 2-kW Single-Phase Seven-Level Flying Capacitor Multilevel Inverter With an Active Energy Buffer , 2017, IEEE Transactions on Power Electronics.

[6]  Robert C. N. Pilawa-Podgurski,et al.  Design of a 1 kV bidirectional DC-DC converter with 650 V GaN transistors , 2018, 2018 IEEE Applied Power Electronics Conference and Exposition (APEC).

[7]  Milan M. Jovanovic,et al.  Design-Oriented Analysis and Performance Evaluation of Buck PFC Front-End , 2009, 2009 Twenty-Fourth Annual IEEE Applied Power Electronics Conference and Exposition.

[8]  Robert C. N. Pilawa-Podgurski,et al.  Design of a GaN-based, 9-level flying capacitor multilevel inverter with low inductance layout , 2017, 2017 IEEE Applied Power Electronics Conference and Exposition (APEC).

[9]  J.W. Kolar,et al.  Design of a 5-kW, 1-U, 10-kW/dm$^{\hbox{3}}$ Resonant DC–DC Converter for Telecom Applications , 2009, IEEE Transactions on Power Electronics.

[10]  Zitao Liao,et al.  A GaN-based flying-capacitor multilevel boost converter for high step-up conversion , 2016, 2016 IEEE Energy Conversion Congress and Exposition (ECCE).

[11]  F.C. Lee,et al.  Input filter design for power factor correction circuits , 1993, Proceedings of IECON '93 - 19th Annual Conference of IEEE Industrial Electronics.

[12]  H. Endo,et al.  A high-power-factor buck converter , 1992, PESC '92 Record. 23rd Annual IEEE Power Electronics Specialists Conference.

[13]  Alex Ruderman,et al.  Six-level single-leg flying capacitor converter voltage balancing dynamics analysis , 2010, Proceedings of 14th International Power Electronics and Motion Control Conference EPE-PEMC 2010.

[14]  Tomas Modeer,et al.  Power-dense multilevel inverter module using interleaved GaN-based phases for electric aircraft propulsion , 2018, 2018 IEEE Applied Power Electronics Conference and Exposition (APEC).

[15]  Yehuda Levy,et al.  Low THD multipliers for BCM buck and cascaded buck-boost PFC converters , 2017, 2017 IEEE Energy Conversion Congress and Exposition (ECCE).

[16]  Michael W. Baker,et al.  Ripple minimizing digital controller for flying capacitor dc-dc converters based on dynamic mode levels switching , 2017, 2017 IEEE Applied Power Electronics Conference and Exposition (APEC).

[17]  Robert C. N. Pilawa-Podgurski,et al.  Design and implementation of a low-cost and compact floating gate drive power circuit for GaN-based flying capacitor multi-level converters , 2017, 2017 IEEE Applied Power Electronics Conference and Exposition (APEC).

[18]  Fred C. Lee,et al.  Design of GaN-based MHz totem-pole PFC rectifier , 2015, 2015 IEEE Energy Conversion Congress and Exposition (ECCE).

[19]  Jason T. Stauth,et al.  A 48V:2V flying capacitor multilevel converter using current-limit control for flying capacitor balance , 2017, 2017 IEEE Applied Power Electronics Conference and Exposition (APEC).

[20]  Zitao Liao,et al.  A 99.1% efficient, 490 W/in3 power density power factor correction front end based on a 7-level flying capacitor multilevel converter , 2018, 2018 IEEE Applied Power Electronics Conference and Exposition (APEC).

[21]  Giorgio Spiazzi,et al.  Analysis of buck converters used as power factor preregulators , 1997, PESC97. Record 28th Annual IEEE Power Electronics Specialists Conference. Formerly Power Conditioning Specialists Conference 1970-71. Power Processing and Electronic Specialists Conference 1972.

[22]  R. J. King,et al.  High performance ripple feedback for the buck unity-power-factor rectifier , 1995 .