Team

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Fellow of IEEE, 2013, Fellow of Canadian Academy of Engineering, 2018

Dr. Yan-Fei Liu received his Bachelor and Master degree from the Department of Electrical Engineering from Zhejiang University, China, in 1984 and 1987 and PhD degree from the Department of Electrical and Computer Engineering, Queen’s University, Kingston, ON, Canada, in 1994.

He was a Technical Advisor with the Advanced Power System Division, Nortel Networks, in Ottawa, Canada from 1994 to 1999. Since 1999, he has been with Queen’s University, where he is currently a Professor with the Department of Electrical and Computer Engineering. Learn more

Contribution to Research

His current research interests are listed as following: 

Best utilization of the benefits of GaN and SiC devices to explore the full advantage of these devices so that small size and high efficiency power converters can be designed

Extremely high efficiency (>99%) and extremely high-power density (>2000W / inch3) DC – DC Bus converter for data center application 

High power density LLC resonant converter for different power level (from 65W to 4000W) for different applications (such as PD adapter, data center power, EV on-board DC – DC converter)  

Digital Control technologies for accurate current sharing of multi-phase interleaved LLC resonant converter to achieve high efficiency and high-power density simultaneously.

Digital control technology for fast dynamic response of DC – DC converters. 

High efficiency, high power density AC to DC power converter for USB C Power Delivery (PD) application using GaN switches. 

On-board EV DC – DC converter with high efficiency and high-power density using GaN switches. 

High power, high efficiency, and high-power density single phase AC – DC rectifier suitable for On-Board Charger using GaN switches.  

Publications

He has authored more than 260 technical papers in the IEEE Transactions and conference (https://www.ece.queensu.ca/people/Y-F-Liu/publications.html), and holds 53 U.S. patents (https://www.ece.queensu.ca/people/Y-F-Liu/publications.html#patent), with more US patent application submitted. He has written a book on “High Frequency MOSFET Gate Drivers: Technologies and Applications”, published by IET. He is also a Principal Contributor for two IEEE standards. He received “Modeling and Control Achievement Award” from IEEE Power Electronics Society in 2017. He received Premier’s Research Excellence Award in 2000 in Ontario, Canada. He also received the Award of Excellence in Technology in Nortel in 1997.  

Contribution to Technology Transfer

Dr. Liu is the co-founder of the following two companies: Potentia Semiconductor in 2001, specializing in power management integrated circuit for flat panel display applications. In Potentia, He was responsible for product roadmap and new product definition and introduction. Potentia was acquired by Power Integration in 2008.  DigiQ Power in 2018, specializing the design of miniature AC to DC power converters. In DigiQ, he is directing the technology development, new production design and introduction, as well as the future growth of the company.

Contribution to IEEE

Dr. Liu is the Vice President of Technical Operations of IEEE Power Electronics Society (PELS, from 2017 to 2020, https://www.ieee-pels.org/technical-activities). He is the general chair of ECCE 2019 held in Baltimore, USA in 2019, http://www.ieee-ecce.org/2019/). Dr. Liu serves as an Editor of IEEE Journal of Emerging and Selected Topics of Power Electronics (IEEE JESTPE) since 2013. His other major service to IEEE is listed below: a Guest Editor-in-Chief for the special issue of Power Supply on Chip of IEEE Transactions on Power Electronics from 2011 to 2013; a Guest Editor for special issues of JESTPE: Miniaturization of Power Electronics Systems in 2014 and Green Power Supplies in 2016; as Co-General Chair of ECCE 2015 held in Montreal, Canada, in September 2015; the chair of PELS Technical Committee (TC1) on Control and Modeling Core Technologies from 2013 to 2016; chair of PELS Technical Committee (TC2) on Power Conversion Systems and Components from 2009 to 2012. 

Dr. Yang Chen (S’14–M’17) received his B.Sc. and M.Sc. degrees in electrical engineering from Beijing Institute of Technology, Beijing, China, in 2011 and 2013, respectively, and his Ph.D. degree in Electrical and Computer Engineering in 2017 from Queen's University, Kingston, Canada.  

During the Ph.D. study, he proposed a series of enhanced LLC topologies and control methods to improve the operational voltage range of LLC converters. He proposed a passive-impedance-matching concept to achieve current sharing among multiple LLC phases without additional switches or control. He also proposed a capacitor by-passing method for LLC converters to achieve universal AC input operation. 

His research interests include topology and control of power converters for data center and server power supplies, miniaturized resonant converters with wide voltage range for notebook and cellphone fast charging, and high-performance DC-DC converters and AC-DC chargers for EVs. 

His innovations have been successfully adopted in multiple industrial sectors. He is the author of more than 36 technical papers published in IEEE journals and conferences. He holds 12 US patents, 4 China patents, and has 8 US/CN/PCT patents pending.