Gridlock in 2030?

A few years ago, former Secretary of Energy Bill Richardson characterized the U.S. electric grid, the system of physical and human systems linking generators to loads, as “third-world.” 1 More recently, others have claimed that smart grid technologies promise to “spur the kind of transformation the Internet has already brought to the way we live, work, play and learn.” [superscript 2

Nonlinear System Modeling, Optimal Cam Design, and Advanced System Control for an Electromechanical Engine Valve Drive

A cam-based shear force-actuated electromechanical valve drive system offering variable valve timing in internal combustion engines was previously proposed and demonstrated. To transform this concept into a competitive commercial product, several major challenges need to addressed, including the reduction of power consumption, transition time, and size. As shown in this paper, by using nonlinear system modeling, optimizing cam design, and exploring different control strategies, the power consumption has been reduced from 140 to 49 W (65%), the transition time has been decreased from 3.3 to 2.7 ms (18%), and the actuator torque requirement has been cut from 1.33 to 0.30 N·m (77%).Sheila and Emanuel Landsman Foundatio

Realistic litz wire characterization using fast numerical simulations

The losses of realistic litz wires are characterized while explicitly accounting for their construction, using a procedure that computes the current-driven and magnetic-field-driven copper losses using fast numerical simulations. We present a case study that examines loss variation in one- and two-level litz wires as a function of twisting pitch, over a wide range of values and in small increments. Experimental confirmation is presented for predictions made by numerical simulations. Results confirm the capability and efficiency of numerical methods to provide valuable insights into the realistic construction of litz wire.MIT Energy InitiativeSingapore-MIT Allianc

Analysis and Control of a Cellular Converter System with Stochastic Ripple Cancellation and Minimal Magnetics

Abstract-A parallel converter architecture based on the resonant pole inverter (RPI) topology is presented. It is shown that this architecture minimizes the output magnetics required for current sharing. A new current control scheme is introduced which reduces peak currents, losses, and output voltage ripple for many operating conditions. This new control method is applicable to both the single RPI and the parallel architecture. Additionally, the paper analytically quantifies the degree of passive ripple cancellation between cells of a parallel architecture. It is shown that the rms ripple current of an N -cell paralleled converter system is a factor of 1= p N lower than for an equivalent single converter. These results are verified using a piecewise-linear model. We conclude that the parallel architecture overcomes some of the major disadvantages of the conventional RPI

Competitive Benchmarking: An IS Research Approach to Address Wicked Problems with Big Data and Analytics

Wicked problems like sustainable energy and financial market stability are societal challenges that arise from complex socio-technical systems in which numerous social, economic, political, and technical factors interact. Understanding and mitigating them requires research methods that scale beyond the traditional areas of inquiry of Information Systems (IS) “individuals, organizations, and markets” and that deliver solutions in addition to insights. We describe an approach to address these challenges through Competitive Benchmarking (CB), a novel research method that helps interdisciplinary research communities to tackle complex challenges of societal scale by using different types of data from a variety of sources such as usage data from customers, production patterns from producers, public policy and regulatory constraints, etc. for a given instantiation. Further, the CB platform generates data that can be used to improve operational strategies and judge the effectiveness of regulatory regimes and policies. We describe our experience applying CB to the sustainable energy challenge in the Power Trading Agent Competition (Power TAC) in which more than a dozen research groups from around the world jointly devise, benchmark, and improve IS-based solutions

A planar germanium thermophotovoltaic energy converter

Massachusetts Institute of Technology. Dept. of Electrical Engineering. Thesis. 1967. E.E.Bibliography: leaves 46-47.by John Gabriel Kassakian.E.E

Effects of firing angle imbalance on 12-pulse rectifiers with interphase transformers

Firing angle or source imbalances between 6-pulse bridges comprising a 12-pulse rectifier lead to current imbalance, due to the finite magnetizing inductance of the interphase transformer. The magnitude of the imbalance is limited by the negative feedback produced by load regulation of the 6-pulse groups. This paper uses both an averaged model and a piecewise-linear simulation to obtain a quantitative understanding of this effect. The averaged model is used to predict steady-state current shifts and transient behavior. The piecewise-linear model of the system is then used to verify and extend the results via computer simulation. It is shown that the current imbalance can be accurately predicted by the averaged model, making the model suitable for both feedback control and interphase transformer design

Analysis and control of a cellular converter system with stochastic ripple cancellation and minimal magnetics

A parallel converter architecture based on the resonant pole inverter (RPI) topology is presented. It is shown that this architecture minimizes the output magnetics required for current sharing. A new current control scheme is introduced which reduces peak currents, losses, and output voltage ripple for many operating conditions. This new control method is applicable to both the single RPI and the parallel architecture. Additionally, the paper analytically quantifies the degree of passive ripple cancellation between cells of a parallel architecture. It is shown that the RMS ripple current of an N cell paralleled converter system is a factor of 1√(N) lower than for an equivalent single converter. These results are verified using a piecewise-linear model. We conclude that the parallel architecture overcomes some of the major disadvantages of the conventional RPI.Bose Foundatio

Distributed interleaving of paralleled power converters

This paper introduces a distributed approach to interleaving paralleled power converter cells. Unlike conventional methods, the distributed approach requires no centralized control, automatically accommodates varying numbers of converter cells, and is highly tolerant of subsystem failures. A general methodology for achieving distributed interleaving is proposed, along with a specific implementation approach. The design and experimental verification of a 50 kHz prototype system is presented, and quantitative performance comparisons are made between synchronized clocking, independent clocking, and interleaved clocking of the converter cells. The experimental results corroborate the analytical predictions and demonstrate the tremendous benefits of the distributed interleaving approach.Bose FoundationUnited States. Office of Naval Researc