A Resonant Switched-Capacitor Converter With GaN Transistors for High-Efficiency Power Delivery to Series-Stacked Processors

The series-stacked architecture provides a method to increase power delivery efficiency to multiple processors by leveraging the inherent voltage step-down properties of series-connected elements. With a series stack, differential power processing (DPP) is needed to ensure that processor voltages remain within design limits, as the individual loads vary. This paper demonstrates a switched-capacitor (SC) converter to balance a stack of four ARM Cortex-A8-based embedded computers. We investigate hard-switched and resonant modes of operation in a ladder SC DPP converter implemented with GaN transistors. Operation within supply limits of each embedded computer is demonstrated in a four-series-stack configuration with realistic computational workloads. Moreover, we demonstrate hot-swapping of individual computers with maintained voltage regulation at all nodes. A peak stack power delivery of 99% is experimentally measured, and DPP switching frequencies from 200 kHz to 2 MHz are demonstrated.

[1]  S. Bahl,et al.  Advantages of GaN in a high-voltage resonant LLC converter , 2014, Applied Power Electronics Conference.

[2]  C. Schaef,et al.  A multi-level ladder converter supporting vertically-stacked digital voltage domains , 2013, 2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[3]  M. D. Seeman,et al.  Resonant Switched-Capacitor Converters for Sub-module Distributed Photovoltaic Power Management , 2013, IEEE Transactions on Power Electronics.

[4]  Robert C. N. Pilawa-Podgurski,et al.  A data-driven approach to the design of photovoltaic maximum power point tracking techniques using field transient data , 2015, 2015 IEEE Energy Conversion Congress and Exposition (ECCE).

[5]  Robert C. N. Pilawa-Podgurski,et al.  A resonant switched-capacitor converter with GaN transistors for series-stacked processors with 99.8% power delivery efficiency , 2015, 2015 IEEE Energy Conversion Congress and Exposition (ECCE).

[6]  Robert C. N. Pilawa-Podgurski,et al.  A high-efficiency high energy density buffer architecture for power pulsation decoupling in grid-interfaced converters , 2015, 2015 IEEE Energy Conversion Congress and Exposition (ECCE).

[7]  Mehdi Ferdowsi,et al.  Double-Tiered Switched-Capacitor Battery Charge Equalization Technique , 2008, IEEE Transactions on Industrial Electronics.

[8]  Philip T. Krein,et al.  Differential Power Processing for DC Systems , 2013, IEEE Transactions on Power Electronics.

[9]  Robert C. N. Pilawa-Podgurski,et al.  A series-stacked architecture for high-efficiency data center power delivery , 2014, 2014 IEEE Energy Conversion Congress and Exposition (ECCE).

[10]  Michael D. Seeman,et al.  Analysis and Optimization of Switched-Capacitor DC–DC Converters , 2008 .

[11]  S. T. Cady,et al.  A Distributed Approach to Maximum Power Point Tracking for Photovoltaic Submodule Differential Power Processing , 2015, IEEE Transactions on Power Electronics.

[12]  Mor Mordechai Peretz,et al.  Enhanced Differential Power Processor for PV Systems: Resonant Switched-Capacitor Gyrator Converter With Local MPPT , 2014 .

[13]  Michael D. Seeman,et al.  The Road to Fully Integrated DC–DC Conversion via the Switched-Capacitor Approach , 2013, IEEE Transactions on Power Electronics.

[14]  Jason T. Stauth,et al.  Multilevel Power Point Tracking for Partial Power Processing Photovoltaic Converters , 2014, IEEE Journal of Emerging and Selected Topics in Power Electronics.

[15]  Gu-Yeon Wei,et al.  A 16-core voltage-stacked system with an integrated switched-capacitor DC-DC converter , 2015, 2015 Symposium on VLSI Circuits (VLSI Circuits).

[16]  R. Pilawa-Podgurski,et al.  Re-thinking data center power delivery: Regulating series-connected voltage domains in software , 2013, 2013 IEEE Power and Energy Conference at Illinois (PECI).

[17]  Jason T. Stauth,et al.  Efficient Voltage Regulation for Microprocessor Cores Stacked in Vertical Voltage Domains , 2016, IEEE Transactions on Power Electronics.

[18]  P. T. Krein,et al.  Overcoming the power wall: Connecting voltage domains in series , 2011, 2011 International Conference on Energy Aware Computing.

[19]  P. T. Krein,et al.  Differential power processing architecture for increased energy production and reliability of photovoltaic systems , 2012, 2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC).

[20]  Philip T. Krein,et al.  Switched capacitor system for automatic series battery equalization , 1997, Proceedings of APEC 97 - Applied Power Electronics Conference.

[21]  Gu-Yeon Wei,et al.  A Fully Integrated Reconfigurable Switched-Capacitor DC-DC Converter With Four Stacked Output Channels for Voltage Stacking Applications , 2016, IEEE Journal of Solid-State Circuits.

[22]  Yutian Lei,et al.  Experimental evaluation of capacitors for power buffering in single-phase power converters , 2015, 2015 IEEE Energy Conversion Congress and Exposition (ECCE).

[23]  Yat Chi Fong,et al.  Topology, Modeling, and Design of Switched-Capacitor-Based Cell Balancing Systems and Their Balancing Exploration , 2017, IEEE Transactions on Power Electronics.

[24]  K. Kesarwani,et al.  A comparative theoretical analysis of distributed ladder converters for sub-module PV energy optimization , 2012, 2012 IEEE 13th Workshop on Control and Modeling for Power Electronics (COMPEL).