Laboratory for Electromagnetic and Electronic Systems
The mission of the Laboratory for Electromagnetic and Electronic Systems (LEES) is to be the focus for research and teaching in electric energy from its production through its processing to its utilization and, in electromechanics, from the macroscopic through the microscopic levels. Electric energy and electromechanics are defined broadly to include power systems monitoring and operation, automatic control, power electronics, high voltage engineering, and conventional, continuum, and biological electromechanics. Much of the work of the laboratory is experimental, and industrial sponsorship represents a large fraction of the laboratory's support. The laboratory's professional staff consists of eight faculty members from Electrical Engineering and Computer Science (EECS), one principal research engineer, one principal research scientist, and approximately 50 graduate students. The laboratory faculty and most of the staff are heavily involved in both undergraduate and graduate teaching. Faculty from the Departments of Mechanical Engineering (ME), Chemical Engineering (CE), and Materials Science and Engineering (DMSE) are collaborators in many of the laboratory's programs, and there are extensive joint activities with the Microsystems Technology Laboratories , the Gas Turbine Laboratory, the Materials Processing Center (MPC), and the Laboratory for Information and Decision Systems.
Professor John G. Kassakian, principal research scientist Dr. Thomas A. Keim, and assistant professor David Perreault lead the laboratory's work in automotive electrical and electronic systems. This work is sponsored primarily through the laboratory's Consortium on Advanced Automotive Electrical and Electronic Components and Systems; a grant from the Sheila and Emanuel Landsman Foundation also supports the work. The consortium, representing almost all of the world's major automobile manufacturers and component suppliers, is truly global and has facilitated international working groups addressing issues of safety, battery/connector design, and arcing faults, all challenges that must be met for the deployment of advanced 42-volt electrical systems.
Professor Perreault and Dr. Keim, working with graduate student Gimba Hassan, have completed the development and experimental validation of a new alternator design that can simultaneously supply power to multiple voltage outputs. This new design is expected to be valuable for automobiles incorporating dual-voltage electrical systems. Working with graduate student Juan Rivas, they have also completed the development of a new control approach for alternators with switched-mode rectifiers that provides substantial increases in output power under low-speed conditions. This work builds on Professor Perreault's earlier research on alternator design, for which two patents were issued this year. Professor Perreault and Dr. Keim are presently working with postdoctoral associate Dr. Saichun Tang to develop a fully packaged (vehicle-ready) alternator incorporating these and other advances.
Professor Kassakian, Dr. Keim, and graduate students Woo Sok Chang, Tushar Parlikar, and Yihui Qui continue to develop an innovative electromagnetic drive for engine valves. This design uses a nonlinear mechanical element to minimize electric power requirements and provides soft landing as an inherent feature of the design rather than as an objective to be achieved by control-system action. This year the predicted characteristics of the design have been demonstrated in a single-valve bench experiment. Industry interest remains high. This work has been sponsored by the Landsman Foundation.
Professors Kassakian and Perreault, Dr. Keim, and graduate students Ivan Celanovic, Frank O'Sullivan, and Natalija Jovanovich are investigating thermophotovoltaic converters for automotive electricity production. Multilayer dielectric stacks functioning as selective bandwidth filters have been fabricated and show great promise to enhance the performance of such systems. Preliminary experimental results of filter performance show good correlation with theory. Ten layer filters are now being fabricated in collaboration with colleagues from the MPC, and a high-temperature emission source has been designed and is in the final stage of fabrication.
Professor George Verghese and Dr. Bernard Lesieutre (now at the Lawrence Berkeley National Laboratory), along with doctoral student Sandip Roy, have continued their study of stochastic network models, originally motivated by efforts to represent cascading failures in power systems. The results have been extended to a large class of models that they term moment-linear stochastic systems, which include as special cases several well-studied models (e.g., jump-Markov models and queuing networks). They have developed a variety of estimation and control results for such models. The work has also led to the construction of an aggregate model for the dynamics of air traffic systems, in collaboration with Dr. Banavar Sridhar at NASA, Ames. Other related work, undertaken in the masters thesis of Carlos Gomez-Uribe, examines how to estimate the evolving status of unobserved sites in a stochastic network from observations at other sites and how to make the required computations tractable by appropriate partitioning. These results have turned out to have interesting connections to the sort of probabilistic inference on networks that is considered in the experts' systems/artificial intelligence literature.
On a different track, Professor Verghese and Dr. Lesieutre have been working with doctoral student Ernst Scholtz to develop observers and observer-based fault detection schemes for the swing dynamics of power networks. They are also developing novel controllers that exploit the wave nature of electromechanical swing disturbances in power systems—for instance, zero-reflection controllers on boundary generators of the system, or zero-transmission controllers on generators at nexus points of the network. Initial results are very encouraging.
Associate professor Steven Leeb and Professor Kirtley have initiated a wide-reaching program with the US Navy to develop dual-use technologies that enhance the performance and operational capabilities of navy ships. A new, almost sensorless hardware monitoring platform, based on the nonintrusive load monitoring (NILM) system under development in LEES, will be created as part of this project. This monitoring platform will provide supervisory control, battle damage assessment, predictive maintenance indications, and power distribution monitoring for all of the significant electrical loads on a warship. Prototype monitoring systems were installed on two operational vessels this year: ONR's YP and Woods Hole's Oceanus. Additional field testing and diagnostic monitoring algorithms will be developed in the coming year.
Professor Leeb and Professor Les Norford of Architecture have demonstrated new opportunities for high-volatage alternating current energy conservation using the NILM this year at 10 different monitoring sites in California.
Professor Perreault and doctoral student Timothy Neugebauer have continued their development of filters and filter components incorporating novel inductance cancellation techniques. This year they have developed and validated design methods for filters incorporating printed circuit board cancellation windings. These new filters provide improvement factors of 10 to 30 in performance over conventional designs at no increase in size or cost. This work was the subject of two publications this year.
Professor Perreault, graduate student Robert Jensen, and Professor Charles Sullivan of Dartmouth University are working together to develop new packaging methods for high-performance power capacitors. The new packaging techniques under development provide environmental protection (e.g., against humidity) while yielding reduced size and improved capacitor electrical performance as compared to conventional packaging methods.
Professors Perreault and Jeffrey Lang and doctoral student Joshua Phinney are engaged in the development of new types of power-passive components that scale well to small sizes and high frequencies. Construction of these components using microfabrication techniques is also being explored, with the goal of enabling integrated fabrication of power converters. Professors Perreault and Kassakian are working with doctoral student Juan Rivas on the development of new circuit architectures and control methods that are well suited to these new component types and that permit the use of greatly increased operating frequencies.
Professor Leeb and his students have developed a new multilevel power converter, the Marx Inverter, that can provide low-distortion waveforms with almost arbitrary shape at power levels in the kilowatt range for a variety of communication and power transfer applications. The converter has been used this year to develop a new semiactive vibration damper that employs magnetically activated gels, developed in LEES, to provide selectively tunable damping frequencies. The converter inductively heats targets in the gel that respond at unique drive frequencies. Applications include medical radiothermy systems that actively control tissue temperature by adjusting drive frequency.
Professor Jeffrey Lang and graduate student J. Lodewyk Steyn, in collaboration with Professor C. Livermore of ME and Dr. S. D. Umans of EECS, have fabricated a set of electric micro-electro-mechanical systems (MEMS) turbine generators that are designed to produce watt-level electrical power. Initial tests have shown that the generators were fabricated as desired. Tests to demonstrate generation are now under way. In parallel, Professor Lang, graduate student Sauparna Das, and colleagues from the Georgia Institute of Technology have designed similar magnetic MEMS turbine generators.
Professor Lang and graduate students Jian Li and Jin Qiu, in collaboration with Professor Alex Slocum of ME, have designed and successfully tested a MEMS zipper actuator that greatly reduces the actuation voltage of the zipper without a loss of force. The actuator has been used to actuate a MEMS relay that, as a consequence of the actuator force, exhibits very high current-carrying capacity.
Professor Markus Zahn and his students have focused on the development of magnetic field-based MEMS devices using magnetic particles and magnetic fluids for such new high-technology applications as sensors, actuators, and biomedical tools. They have been the first to measure and explain paradoxical "negative-viscosity" measurements in rotating magnetic fields, whereby the approximately 10-nm-diameter nanomagnets are spinning, making the ferrofluid act as if it were filled with nanogyroscopes. These spinning nanomagnets result in viscous and Maxwell stress tensors that have an antisymmetric part and result in new ferrohydrodynamic phenomena that may have applications in microfluidic devices. They have also derived magnetic field effects on ferrofluid meniscus shapes in competition to surface tension, which is very important in microdevices, and they have demonstrated ferrofluid behavior in sheet flows with magnetic fields, whereby a ferrofluid jet impacts a fixed plate, forming radially expanding flows of microscopic thickness, fluid bells, or elliptic-like elongated shapes.
Professor Zahn and graduate student Jason Sears have been extending past research on interdigital dielectrometry and magnetometry sensors to security detection and identification of hidden dangerous materials. This work has important implications for airport security and land mine detection systems. Preliminary dielectrometry measurements of shoes with a hidden cavity filled with different materials have demonstrated the ability of this technology to detect hidden materials in shoes. New dielectrometry sensors with electric field penetration depth up to » 10 cm have been designed, fabricated, and analyzed. Finally, finite element analysis has been used to design greater penetration depth sensors with small sensor footprints using segmented electrodes.
Joel Schindall '63 has returned to MIT as the Bernard Gordon professor of the practice in electrical engineering and has joined the LEES faculty. His charter is to share his experience in the business and entrepreneurial aspects of product development and to develop courses in product design and project management. The context of his initial research is automotive electronics.
Administrative secretaries Karin Janson-Strasswimmer and Kiyomi Boyd have received School of Engineering Infinite Mile Awards for their dedicated and generous service to LEES and its students.
Professor Zahn and undergraduate student C. Lorenz prepared a ferrofluid electrodynamics video that was one of 5 winners from 25 entries in the American Physical Society's Division of Fluid Dynamics 20th Annual Gallery of Fluid Motion.
Professor Zahn was selected to be the first James R. Melcher Memorial Lecturer at the first Joint Meeting of the IEEE-IAS and Electrostatics Society of America in June 2003.
Professor Leeb received an R&D 100 Award for his Talking Lights system.
Professor Kassakian received the European Power Electronics Association Outstanding Achievement Award for his contributions to teaching and research.
More information about the Laboratory for Electromagnetic and Electronic Systems can be found on the web at http://mit42v.mit.edu/lees/.