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 seven faculty from EECS, one Principal Research Engineer and two Research Scientists, 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), Materials Science and Engineering (MS&E) and Nuclear Engineering (NE) are collaborators in many of the laboratory's programs, and there are extensive joint activities with the Microsystems Technology Laboratory (MTL) and the Laboratory for Information and Decision Systems (LIDS).
During the past year the laboratory has experienced an 11 percent increase, to 51 companies, in its Consortium on Advanced Automotive Electrical/Electronic Components and Systems (the "Automotive Consortium") membership, demonstrated several new technologies for improving the reliability and capacity of electric utility systems, demonstrated for the first time a magnetic field based nanoactuator, developed an innovative design for an electromechanical automotive valve train, and demonstrated "Talking Lights" in the Spaulding Rehabilitation Hospital as an assistive device for the blind, hard-of-hearing, and brain injured patients. LEES also received an IR100 Award for innovative product design, and one of its staff members received the Institute of Electrical and Electronics Engineers' (IEEE) Outstanding Young Power Electronics Engineer award.
Professor John G. Kassakian, Principal Research Scientist Dr. Thomas A. Keim, and Research Scientist Dr. 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. The consortium membership now numbers 51, an increase of five from one year ago, and membership is truly global, with more Asian-based member companies than North American companies, and a substantial European representation as well. Almost all of the world's major automobile manufacturers and component suppliers are members. The consortium 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 Kassakian, Dr. Keim, and graduate student Woo Sok Chang have developed an innovative electromagnetic valve drive. This new design minimizes 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.
Dr. Keim, Professor Zahn, and graduate student Alan Wu have completed an investigation of intermittent arcs in high-voltage automotive electrical systems. This work showed that arcs in 42-Volt electrical systems typically dissipate 50 or 100 times as much energy as arcs in 14-Volt systems. This work, along with parallel work by Jeremy Patterson at Tyco Electronics, was presented at a consortium meeting in Nagoya. As a result of this work, arc behavior is widely appreciated as one of the most important elements in the design of 42-Volt systems, and the industry is rapidly developing elegant solutions to this challenge.
Over the last two years, Dr. Perreault and graduate student Timothy Neugebauer have focused on the design of dc/dc converters for automotive applications using Computer Aided Design (CAD) optimization methods. A highly optimized dc/dc converter for automotive applications has been developed using these new methods. It is less than one quarter the size of prototypes previously developed in the lab, and prototype units will soon be delivered to over 15 automotive consortium member companies.
The consortium held meetings in Nagoya, Japan, and Lisbon, Portugal in the past year. The meeting in Nagoya, co-hosted by Toyota, was an exceptional gathering. Attendance approached 300, and the technical content was quite high. The readiness of the Japanese supplier base was dramatized by an exhibition, organized by Toyota. The meeting in Lisbon, co-hosted by Visteon, was also a success. The exhibition at this meeting was limited to Visteon developments. The extent of the work by one company provided further evidence of the rapid progress of the technology.
Last year, we reported that graduate student Edward Lovelace, Dr. Thomas Keim, and Professor Jeffrey Lang, in collaboration with Professor Thomas Jahns of the University of Wisconsin, had proposed and designed a high-power starter-alternator for automobiles of the future. That new machine promised to be more compact, more efficient and less expensive than separate scaled-up versions of traditional starters and alternators taken together. During this past year, in collaboration with the Ford Motor Company, we constructed an experimental starter-alternator, and graduate student David Wentzloff is now in the process of testing it. Our initial test results support the promise of improved performance.
Utility industry restructuring has placed an intense focus on achieving economically optimal system operation by employing new and more sophisticated control and monitoring strategies. LEES has been making significant contributions to the solutions of problems of power system modeling, economic control, and apparatus monitoring.
Monitoring of Power Apparatus and Systems
Professor Steven Leeb, in collaboration with Professor Les Norford in the Architecture department, has initiated an aggressive monitoring program to identify conservation opportunities that could mitigate problems with the electric utility in California. This program is funded in part by the California Energy Commission. Ten sites in San Francisco and Los Angeles will be monitored using the nonintrusive load monitoring (NILM) technology developed by Professor Leeb's group. The NILM provides quick, inexpensive installation and data collation, and is proving to be an ideal platform for power quality monitoring and electromechanical system identification. During the past year, students in Professor Leeb's research group have added networking and diagnostic capabilities to the NILM. The NILM can identify improper or inefficient operation of the electromechanical plant in buildings and report this information anywhere in the world via the worldwide web. This information is being used at MIT to identify significant opportunities to improve the efficiency and reliability of the electric service and electromechanical plant (e.g., Heating, Ventilating, and Air-Conditioning (HVAC) installations, in buildings). The first two NILM installations were conducted in San Francisco and Los Angeles in March 2001.
Research Engineer Mr. Wayne H. Hagman and his students, in concert with Entergy Corporation, have developed a method for predicting in real-time, up to fifteen hours ahead, the load-carrying capacity of power transformers used by electric utilities. Mr. Hagman and his students are presently implementing this method, in a field test installation, on two transformers in the New Orleans area. The installation will include a data link into the Entergy System Control Center to provide system operators with dynamic rating information for use in power dispatching decision-making.
A new method for the early detection of need-for-service and wear out which are applicable to power transformers and other oil insulated power apparatus has been developed by Dr. Chathan Cooke and his graduate student, Timothy Cargol. The goal for this work is the automated in-service detection of degradation of insulating oil used in power apparatus. Past experience indicates that trouble in the tap changer compartment is the most likely cause for transformer failure and hence the focus of this effort is on the tap-changer. A demonstration system for the specific example of tap-changer oil in a power transformer has been constructed, lab-tested and recently installed on an operating transformer on the network of Entergy Services Inc. This system incorporates automated operation and network communications to enable significant cost savings as well as more reliable operations. The in-service performance of the automated diagnostics will be evaluated during the next year.
Modeling of Power Systems
Professors George Verghese and Bernard Lesieutre, along with their students, have been extending their study of a model they introduced last year for networked Markov chains whose transitions are influenced by the states of their neighbors. This "influence model" combines analytical tractability with an ability to capture some of the structure that is of interest in studying networked systems. The effort is being carried out under a U.S. Air Force Office of Scientific Research University Research Initiative (AFOSR URI) grant awarded this year to MIT (jointly with Stanford, University of Illinois-Urbana, and Caltech). The influence model has garnered significant interest from various researchers.
High Voltage and Insulation Research
Dr. Cooke and undergraduate student Daniel Santos are working on a project to reduce the adverse effects of transients and wind-driven fatigue on overhead power lines. Many in-service power lines fail due to mechanical high-cycle fatigue induced by Aeolian vibrations for wind speeds typically in the 5 to 10 miles per hour range. Extensive modeling for vibration modes and frequency dependent damping have been developed to represent typical vibrations versus wind speed. The goal is to introduce damping that reduces vibrational bending so that longer life operation can be achieved. Bench size models have been used to demonstrate the method and larger scale tests are being planned. In the next year wind-tunnel tests are planned to quantify the actual damping of a model line exposed to controlled winds and to demonstrate improved damping.
Dr. Perreault and graduate student Joshua Phinney have completed development of a new filtering technique for power electronics that employs active tuning control. The new technique allows dramatic reduction in the size of the passive filter elements used in power electronics. Reductions of over a factor of three in size and weight as compared to conventional designs have been demonstrated. Dr. Perreault and Mr. Phinney have also developed a passive inductance cancellation technique that greatly improves the performance of power capacitors at high frequencies. Initial experiments have demonstrated over a factor of 10 improvements in noise suppression performance with this new design method, and much greater improvements are expected to be possible. Dr. Perreault and graduate student Albert Chow have developed a new active ripple filter method for power electronics. This new technique greatly reduces the size of filter capacitors needed in many power electronics designs, and may have particular value in aerospace applications where capacitor type and size is a critical factor. These new filtering approaches are expected to be valuable in a wide range of power electronics applications.
Professor George Verghese has co-edited (with Professor Soumitro Banerjee of IIT Kharagpur, India) an IEEE Press/Wiley book titled Nonlinear Phenomena in Power Electronics: Attractors, Bifurcations, Chaos, and Nonlinear Control, which contains contributions from around thirty authors (including several sections coauthored by Professor Verghese). This volume, which has just been published, is the first to be entirely devoted to nonlinear behavior in switched circuits. It has been tightly edited and contains an index, to increase its usefulness to researchers and practitioners in power electronics.
Professor Leeb's Talking Lights have been installed at the Spaulding Rehabilitation Hospital. The Talking Lights system uses conventional fluorescent lamps already in use for illumination in a building to create an inexpensive data network. A Talking Lights electronic ballast modulates the arc in a fluorescent light, transmitting information to an optical receiver with no visible flicker in the lamplight. At Spaulding Talking Lights are serving as assistive devices, providing location and wayfinding information for the blind, hard-of-hearing, and for brain injury patients.
Graduate student Hur Koser and Professor Jeffrey Lang, in collaboration with Professor Mark Allen and his students at the Georgia Institute of Technology, and many students, staff and faculty at MIT, have completed the design and fabrication of a new micro-scale magnetic induction motor. The first-generation motors exhibit torque densities equal to those of existing electric micro-scale motors, but without laminated stators. Second-generation magnetic motors, with laminated stators, are currently under development, and their torque densities are expected to greatly exceed those of the existing electric and magnetic micro-scale motors.
Graduate student Jin Qiu and Professor Lang, in collaboration with Professor Alex Slocum of ME, have designed, fabricated and demonstrated a new mechanically-bistable micromechanical mechanism. The mechanism is very simple to fabricate, and its characteristics are very easy to control. Therefore, it should have wide application to micromechanical relays, fasteners and memories. They are currently working to develop this mechanism into a solid-state relay suitable for use in low-voltage residential and commercial applications.
Professor Zahn has received a three-year program funded by the National Science Foundation to develop magnetic field based Micro-Electromechanical Systems (MEMS) and microfluidic technologies using 10 nm diameter single domain permanently magnetized ferromagnetic spheres with and without a carrier fluid. This research program will explore a new class of magnetic devices with such applications as nanoduct flows, pumps, and nanomotors. Another type of application being explored is the use of a wax based ferrofluid which is solid at room temperature but flows at slightly elevated temperatures. External magnetic fields can shape the material when fluid, and the shape is maintained when the fluid is cooled and the field removed. Such a process can, for example, be used to form nanogears or sharp needle-like peaks for charge injection devices. These formations have been demonstrated.
Graduate student Tim Denison completed a Ph.D. thesis co-supervised by Professor Leeb this year involving the development of a new, super-low noise electrometer. In collaboration with researchers at Harvard and the Rowland institute, this electrometer was used to develop a nano-scale "Coulter Counter" that can be used to quickly identify DNA sequences passing through a pore in an electrochemical cell. This technique has been successfully demonstrated for a variety of identification scenarios, including the recognition of hybridized DNA strands consisting of unknown or "test" DNA bonded to probe strands.
Former Research Scientist Dr. David Perreault was hired by the Department of Electrical Engineering and Computer Science as an Assistant Professor. He is also the 2001 recipient of the IEEE's Richard M. Bass Outstanding Young Power Electronics Engineer award which recognizes outstanding achievement in the field of power electronics by an engineer less than 35 years old.
Professor Zahn has been awarded the Thomas and Gerd Perkins Professorship.
Professor Leeb received an R&D 100 award and was also awarded US Patent 6198230 for his Talking Lights technology.
More information about the Laboratory for Electromagnetic and Electronic Systems can be found online at http://web.mit.edu/lees-lab/www/.