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Dartmouth Engineer - The Magazine of Thayer School of EngineeringDartmouth Engineer - The Magazine of Thayer School of Engineering

Professor Charles Sullivan: Engineer, teacher, inventor

By Anna Fiorentino
February 2014 • Thayer By Degrees: MEM

Charles Sullivan
Professor Charles Sullivan

The Institute of Electrical and Electronics Engineers (IEEE) recently named Professor Charles Sullivan a 2014 Fellow for his contributions to the design of power electronic circuits and magnetics. The award came shortly after Sullivan issued his 31st patent with Dartmouth engineering professor Victor Petrenko for a “Compact helical heat exchanger with stretch to maintain airflow.” With no shortage of new ideas, Sullivan also serves as academic and project advisor for ENGM 178: Technology Assessment and ENGG 390: MEM Project/Internship, and teaches several MEM students in ENGG 173: Energy Utilization. “I hope to have some of my existing or future Dartmouth patents become as valuable as the ones that have been owned by companies,” says Sullivan.

Below are just a few of the inventions he’s helped conjure up over the years:

Voltage converter (aka "Voltage converter with coupled inductive windings, and associated methods"): In 2002, when Sullivan was a consultant for a Silicon Valley startup that aimed to provide power to microprocessors called Volterra, he designed this high-efficiency voltage converter with the fast response to allow a microprocessor to respond immediately without power supply glitches, preventing computer crashes. “It’s a way to get around the usual tradeoff between fast response and efficiency in that type of converter,” says Sullivan. Shortly afterwards, Volterra sponsored Jieli Li Th’02 who developed the technology further and eventually went to work for Volterra before moving on to Apple. Li and Sullivan continued to collaborate on a number of different inventions that were later issued patents. “The products that were based on that patent have been deployed in more than 25 million servers and notebook computers and Volterra estimates that it has saved a massive amount of electricity consumption,” says Sullivan. “That technology was one of the reasons that Maxim Integrated acquired Volterra this year.” The circuit approach has advantages in other applications as well and is starting to be used more widely in electric vehicles and smart grid applications, for example.

Refrigerator anti-froster (aka “Compact helical heat exchanger with stretch to maintain airflow”): With Petrenko as first inventor, Sullivan played a supporting role in this most recent patent, issued last April. The invention sheds frost build-up from refrigerator cooling coils by exchanging heat between gasses and a liquid or gaseous coolant and reducing the spacing between exchanger surfaces for higher efficiency. “It allows you to maintain peak performance as the frost builds up,” says Sullivan. “Add that to the fact that the performance starts out better than a conventional coil, plus lowers energy use during defrosting, and you have the capability to make substantial performance improvements.”

Fluorescent lamp dimmer (aka "Circuit for dimming gas discharge lamps without introducing striations"): Sullivan’s first patent issued in 1992 while he was working as a junior engineer for Lutron Electronics in Pennsylvania. “It saves energy by using fluorescents instead of incandescents in applications like classrooms,” Sullivan points out. It was a bonus that when he later began teaching at Dartmouth, Sullivan discovered his system, which has been produced for decades now, was being used in the college’s classrooms.

DNA transformer (aka “Method and apparatus for bacterial transformation by electroporation with waveforms incorporating pulsed RF between 3 and 125 MHz”): For this patent issued in 2007, Sullivan worked outside his usual area of expertise with Professor Lee Lynd's group studying and developing equipment for transforming the DNA in bacteria. “It's a great example of the kind of collaboration that can happen at Thayer and probably would not happen anywhere else,” he says.

Tags: award, energy, faculty, innovation, patent

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