United States of America
Professor Rivas came to Stanford as an assistant professor in January 2014. He was an assistant professor in Electrical Engineering at the University of Michigan. Before becoming a faculty member in 2011, he worked for the General Electric Global Research Center developing power electronics for medical imaging and aviation systems. He received the B.Sc. degree in electrical engineering from the Monterrey Institute of Technology (Mexico) in 1998. He obtained his masters (2003) and doctoral degree (2006) at the Massachusetts Institute of Technology. His research interests are in power electronics, RF power amplifiers, resonant converters, soft switching topologies and design of power converters for operation in harsh environments.
Modern applications are driving demand for power systems with capabilities beyond what is presently achievable. High performance systems, like medical imaging systems and other applications impose challenging specifications on power density and bandwidth that are difficult to achieve with current circuit topologies. Power density can be improved with better semiconductor components and passive elements, and by reducing the energy storage requirements of the system. By dramatically increasing the switching frequency, it is possible to reduce the energy storage requirements and improve bandwidth. I'm interested in the development of system architectures and circuit topologies for dc-ac and dc-dc power conversion that can reach switching frequencies of 10’s to 100’s of MHz. Switching at these frequencies will lead to efficient converters with inductors and transformers having no magnetic material to limit their high frequency performance, and with small-valued capacitors. At these switching frequencies, all inductors can be air-cored, eliminating core losses, saturation, and extending their operating temperature range. I have been involved in the development of dc-dc converter that archives a significant reduction in peak switch voltage stress, requires small passive components with low energy storage, and provides the capability for extremely rapid startup and shutdown. Another goal of my work is to implement a value-added strategy in inexpensive printed circuit boards (PCB) by fabricating all passive devices of a power converter (inductors and capacitors) with traces, transforming the PCB into a 3-D resonant structure. This approach will eliminate tuning and component variation while simultaneously maintaining extraordinary levels of performance at reduced cost. Moreover, there a lot of exciting applications for these high frequency circuits.
Raymond L, Liang W, Choi J, Rivas J. 27.12 MHz large voltage gain resonant converter with low voltage stress. InEnergy Conversion Congress and Exposition (ECCE), 2013 IEEE 2013 Sep 15 (pp. 1814-1821). IEEE.
Liang W, Glaser J, Rivas J (2015) 13.56 MHz high density DC–DC converter with PCB inductors. IEEE Transactions on Power Electronics 30: 4291-4301.