Research â€” Ellis Power Group

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Our Projects

Please browse our current and past research projects below.

A High Step-Down Hybrid Switched-Capacitor DC-DC Converter for High Voltage Space Applications

This work presents a lightweight hybrid switched-capacitor (HSC) DC–DC converter for future space power systems, addressing the mass, efficiency, and environmental constraints of next-generation space applications.

In Progress

Automatic Balancing of Flying Capacitor Voltages through Deterministic Switching States

This work investigates hybrid-switched-capacitor power converter architectures capable of imposing deterministic flying capacitor voltage biases without incurring additional loss in periodic steady-state, under both loaded and unloaded conditions.

In Progress

High-Density Radiation-Hardened Point-of-Load Power Conversion Using Hybrid-Switched-Capacitor Circuit Topologies

High-Density Radiation-Hardened Point-of-Load (PoL) Power Conversion Using Hybrid-Switched-Capacitor Circuit Topologies

This work reviews recent advances in hybrid switched-capacitor (HSC) ladder converters and their potential for radiation-hardened point-of-load power conversion, including direct 48V-to-1V conversion. A representative hardware prototype highlights the technology's readiness for aerospace applications.

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Past Projects

The projects below were completed with Prof. Ellis as first author at institutions prior to joining UC Santa Cruz, including UC Berkeley's Berkeley Power and Energy Center and UC Davis.

Gallium Nitride-Based 48 V-to-1 V Point-of-Load Converter

A Gallium Nitride-based 48V-to-1V Point-of-Load (PoL) Converter for Aerospace Telecommunications and Computing Applications

Best-in-class power-density and efficiency at the time of publication. This converter is roughly the size of your thumbnail while delivering 60A.

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A General Analysis of Resonant Switched-Capacitor Converters Using Peak Energy Storage and Switch Stress Including Ripple

This work provides a theoretical foundation for designing high-performance resonant switched-capacitor converters.

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The Symmetric Dual Inductor Hybrid Converter for Direct 48V-to-PoL Conversion

A new power converter topology, elegantly derived from the well-known series-capacitor-buck converter.

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Large Signal Analysis on Variations of the Hybridized Dickson Switched-Capacitor Converter

This work characterizes a sub-set of hybrid switched-capacitor converters known as "Dickson"-type; those with the best volt-amp switch performance. Several new structures are presented alongside contemporary work within the same class. Includes indepth discussion on trade-offs, characteristics and operability of each topological structure.

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Closed-Loop Split-Phase Control Applied to the Symmetric Dual Inductor Hybrid (SDIH) Converter

"Split-phase" control is an advanced clocking technique that allows some switched-capacitor converters to overcome inherent hard-charging limits. However, accurate implementation of this technique for practical adoption may require closed-loop control.

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An Actively Balanced Distributed Regenerative Snubber with Reduced Part Count in Multi-Level Power Converters

As converters become more complex, further opportunities arise for regenerative energy harvesting within the power stage (boosting efficiency). This works presents a snubber solution whose complexity needn't necessarily grow with level count.

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Modified Split-Phase Switching with Improved Fly Capacitor Utilization in a 48V-to-POL Dual Inductor Hybrid-Dickson Converter

A new control strategy for split-phase switching in hybrid switched-capacitor converters, leading to improved utilization of fly capacitors and enhanced performance.

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A Synchronous Boot-strapping Technique with Increased On-time and Improved Efficiency for High-Side Gate-drive Power Delivery

High-side gate-drive power delivery is a limiting aspect of many power converter designs. Cascaded bootstrapping for high-side power delivery is extremely compact but also historically inefficient and unidirectional. This work demonstrates an alternative.

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A Resonant Dual Extended LC-tank Dickson Converter with 50% Two-Phase Operation at Odd Conversion Ratios

A new Dickson converter with attractive features. This circuit topology has served as a cornerstone for several subsquent works.

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Reducing C_OSS Switching Loss in a GaN-based Resonant Cockcroft-Walton Converter Using Resonant Charge Redistribution

A lucrative circuit trick, exercised during deadtime intervals, that leads to dramatic loss reductions in eligible circuit topologies. Demonstrated in a resonant Cockcroft-Walton converter.

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A Resonant Gate Driver with Variable Gain and a Capacitively Decoupled High-Side GaN-FET

Welcome to the world of adiabatic gate drivers. How much energy does it take to turn on a switch?

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A Resonant 1:5 Cockcroft-Walton Converter Utilizing GaN FET Switches with N-Phase and Split-Phase Clocking

There are different ways to skin a cat. This work demonstrates two advanced and complimentary clocking techniques for the same piece of hardware (plus a neat high-side gate drive power delivery scheme).

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A Resonant Cockcroft-Walton Switched-Capacitor Converter Achieving Full ZCS and >10kW/inch3 Power Density

A Resonant Cockcroft-Walton Switched-Capacitor Converter Achieving Full ZCS and >10kW/inch³ Power Density

Proof-of-concept hardware using a spiral trace inductor to minimize converter volume.

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