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  • Journal article
    Banaji M, Angeli D, 2012,

    CONVERGENCE IN STRONGLY MONOTONE SYSTEMS WITH AN INCREASING FIRST INTEGRAL (vol 42, pg 334, 2010)

    , SIAM JOURNAL ON MATHEMATICAL ANALYSIS, Vol: 44, Pages: 536-537, ISSN: 0036-1410
  • Conference paper
    Elliott ADT, Mitcheson PD, 2012,

    Implementation of a Single Supply Pre-biasing Circuit for Piezoelectric Energy Harvesters

    , Eurosensors 2012, Pages: 1311-1314
  • Journal article
    Angeli D, Amrit R, Rawlings J, 2012,

    On average performance and stability of economic model predictive control

    , IEEE Transactions on Automatic Control

    Control performance and cost optimization can beconflicting goals in the management of industrial processes.Even when optimal or optimization-based control synthesis tools are applied, the economic cost associated with plant operation is often only optimized according to static criteria that pick,among all feasible steady states, those with minimal cost. In mathematical terms an economic cost functional differs from stage costs commonly adopted in MPC as it need not be minimalat its best equilibrium.This note collects and illustrates some recent advances in receding horizon optimization of nonlinear systems that allow the control designer to simultaneously and dynamically optimize transient and steady-state economic performance.In particular, we show that average performance of economic MPC is never worse than the optimal steady-state operation. We introduce a dissipation inequality and supply function that extend previous sufficient conditions for asymptotic stability of economic MPC. Dissipativity is also shown to be a sufficient condition for concluding that steady-state operation is optimal. We show how to modify an economic cost function so that steady-state operation is asymptotically stable when that feature is deemed desirable. Finally, for the case when steady-state operation is not optimal, we develop two modified MPC controllers thatasymptotically guarantee (i) improved performance compared to optimal periodic control and (ii) satisfaction of constraints on average values of states and inputs.
  • Conference paper
    Kerrigan EC, Jerez JL, Longo S, Constantinides GAet al., 2012,

    Number Representation in Predictive Control

    , IFAC Conference on Nonlinear Model Predictive Control 2012 (NMPC'12), Publisher: IFAC

    We will present some of the lessons that we have learnt at Imperial College London while implementing predictive controllers on embedded systems. In particular, we will discusssome of the advantages and issues that arise when one does not use IEEE double-precisionoating-point to solve the resulting optimization problems, as well as some initial suggestions on how to overcome certain problems.
  • Conference paper
    Elliott ADT, Mitcheson PD, 2012,

    Power Density Improvement of a Piezoelectric Energy Harveter Using a Micropower Switch-Mode Interface

    , IEEE Sensors 2012, Publisher: IEEE, Pages: 1882-1885
  • Conference paper
    Elliott ADT, Zhu D, Beeby SP, Mitcheson PDet al., 2012,

    Multilayer Piezoelectric Energy Harvesting Using Single Supply Pre-biasing for Maximum Power Generation

    , PowerMEMS 2012
  • Conference paper
    Elliott ADT, Mitcheson PD, 2012,

    Implementation of Single Suply Pre-Biasing with Sub-35μW Control Overhead for Piezoelectric Energy Harvesting

    , PowerMEMS 2012
  • Conference paper
    Kiziroglou ME, Wright SW, Toh TT, Becker T, Mitcheson PD, Yeatman EMet al., 2012,

    Heat Storage Power Supply for Wireless Aircraft Sensors

    , Pages: 472-475
  • Conference paper
    Kaphengst NF, Toh TT, Mitcheson PD, Holmes AS, Wright SW, Yeatman EMet al., 2012,

    Adaptive Load Synthesis for Autonomous Resonant Frequency Tuning of Electromagnetic Energy Harvesters

    , PowerMEMS 2012
  • Conference paper
    Bowden J, Burrow SG, Cammarano A, Mitcheson PDet al., 2012,

    Synthesising Load Impedance to Frequency-Tune an Electro-Mechanical Vibration Energy Energy Harvester

    , ASME 2012 International Design Engineering Technical Conferences
  • Conference paper
    Mukherjee AG, Mitcheson PD, Wright SW, Yeatman EMet al., 2012,

    Magnetic Potential Well Tuning of Resonant Frequency Cantilever Energy Harvesters

    , PowerMEMS 2012
  • Report
    Cain MG, Mitcheson PD, 2012,

    Rectification of harvested energy in vibrational energy harvesting materials technologies: Materials, power systems design and electronic engineering issues
  • Conference paper
    Mylvaganam T, Astolfi A, 2012,

    Approximate Optimal Monitoring: Preliminary Results

    , American Control Conference (ACC), Publisher: IEEE COMPUTER SOC, Pages: 4745-4750, ISSN: 0743-1619
  • Conference paper
    Sassano M, Passenbrunner TE, Hirsch M, del Re L, Astolfi Aet al., 2012,

    Approximate Optimal Control of the Air Path of a Diesel Engine

    , American Control Conference (ACC), Publisher: IEEE COMPUTER SOC, Pages: 4204-4209, ISSN: 0743-1619
  • Conference paper
    Sassano M, Astolfi A, 2012,

    Dynamic Lyapunov Functions: Properties and Applications

    , American Control Conference (ACC), Publisher: IEEE COMPUTER SOC, Pages: 2571-2576, ISSN: 0743-1619
  • Conference paper
    Longo S, Kerrigan EC, Ling KV, Constantinides GAet al., 2011,

    Parallel Move Blocking Model Predictive Control

    , 50th IEEE Conference on Decision and Control and European Control Conference, Publisher: IEEE

    This paper investigates the use of parallel computing architectures (multi-core, FPGA, GPU) to implement a parallel move-blocking Model Predictive Control (MPC) algorithm where multiple optimization problems are solved simultaneously. Since smaller problems are solved, and these are solved in parallel, the computational delay is reduced when compared to standard MPC. This allows for faster sampling which can outperform, in terms of closed-loop cost, a standard MPC formulation. Feasibility and stability can be guaranteed by an appropriate selection of the so-called blocking matrices.
  • Conference paper
    Pipelzadeh Y, Chaudhuri B, Green TC, 2011,

    Coordinated Damping Control Through MultipleHVDC Systems: A Decentralized Approach

    , IEEE Power and Energy Society General Meeting 2011

    The role of multiple HVDC links - both CSC and VSC - in improving the AC system dynamic performance is presented here. An Australian equivalent system with three critical interareamodes is considered to illustrate the case study on DIgSILENT PowerFactory. Subspace-based multi-input-multi-output(MIMO) system identification is used to estimate and validatelinearized state-space models through pseudo random binary sequence (PRBS) probing in DIgSILENT PowerFactory. Choice of appropriate input-output combinations is done through modalresidue analysis taking note of not only the magnitudes but also the phase angles. The decentralized control design is posed as an optimization problem and solved using an evolutionary technique. The results are validated through linear analysis andnon linear simulation in DIgSILENT for two extreme (light and heavy loading) operating conditions.
  • Conference paper
    Boem F, Pellegrino FA, Fenu G, Parisini Tet al., 2011,

    Multi-feature trajectory clustering using Earth mover's distance

    , Pages: 310-315, ISSN: 2161-8070

    We present new results in trajectory clustering, obtained by extending a recent methodology based on Earth Mover's Distance (EMD). The EMD can be adapted as a tool for trajectory clustering, taking advantage of an effective method for identifying the clusters' representatives by means of the p-median location problem. This methodology can be used either in an unsupervised fashion, or on-line, classifying new trajectories or part of them; it is able to manage different length and noisy trajectories, occlusions and takes velocity profiles and stops into account. We extend our previous work by taking into account other features besides the spatial locations, in particular we consider the direction of movement in correspondence of each trajectory point. We discuss the simulation results and we compare our approach with another trajectory clustering method. © 2011 IEEE.
  • Conference paper
    Pipelzadeh Y, Chaudhuri B, Green TC, 2011,

    The Impact of Significant Wind Penetration and HVDC Upgrades on the Stability of Future Grids: A Case Study on the Australian Power System

    , CIGRE International Symposium 2011

    Wind power has been the fastest growing energy generation sector worldwide in recent years. Large on- and off-shore wind farms have a considerable impact on system security and stable system operation. Therefore its influence on the dynamic stability of the system must be addressed. For turbines above 1MW, doubly-fed induction generators (DFIG) are the most widely used concept. However in many countries such as U.K and Germany, full-rated converter (FRC) have also gained vast amount of market penetration.To address this, the paper presents studies performed in DIgSILENT PowerFactory aimed at ascertaining the impact that DFIG and FRC have on the oscillation modes of the power system. The feasibility, advantage and disadvantages of various options are discussed.Wind generators can be connected to existing power transmission networks spanning over long distances and ultimately causing interaction between wind-farms and transmission systems. The benefit of utilising HVDC (classical and/or Voltage- source) within an ac network for transporting large amounts of wind power to remote load locations is studied.Wind farms consist of large number of generators of relatively small size. Both types of variable speed wind generators (DFIG and FRC) have been modelled in detail in PowerFactory DIgSILENT. Model aggregation techniques are applied to reduce computation time. Different control strategies for VSC-HVDC and “classical” Thyristor-based HVDC links are presented and analyzed via network simulation. A case study is presented based on the equivalent SE Australian power system, an IEEE benchmark system for dynamic studies, with appropriate reinforcements introduced to accommodate wind generation and HVDC transmission systems.This paper is focused on the small-signal stability issues and analyses the impact of various aspects like generator technology, hybrid AC/HVDC transmission for getting a thorough understanding about the impact of these on the overall system sta
  • Journal article
    Wu R, Sin JKO, Hui SY, 2011,

    A novel silicon-embedded coreless transformer for isolated DC-DC converter application

    , Proceedings of the International Symposium on Power Semiconductor Devices and ICs, Pages: 352-355, ISSN: 1063-6854

    In this paper, a novel silicon-embedded coreless transformer (SECT) is proposed and demonstrated for isolated dc-dc converter applications. By embedding two interleaved thick Cu coils in the bottom layer of the Si substrate, the designed 2 mm2 SECT can achieve a maximum transformer efficiency of 85% at 50 MHz. Compared to the on-silicon coreless power transformer reported earlier for 0.5 W isolated dc-dc conversion at 170 MHz with a transformer efficiency of over 70%, the much lower operating frequency of the SECT allows the power losses of the power MOSFETs and Schottky diodes to be reduced by around 50%, leading to a converter loss reduction of 38%. Since only 4 vias are opened at the top layer of the substrate, most of the top layer of the substrate can be used for power IC implementation to achieve efficient monolithic integration. Experimental results show that the SECT provides a maximum transformer efficiency of 73% at 50 MHz, which is lower than expected and due to the non-optimized isolation oxide used. © 2011 IEEE.
  • Journal article
    Hui SY, Chung HSH, 2011,

    Resonant and soft-switching converters

    , Pages: 409-453

    This chapter covers the basic technology of resonant and soft-switching converters. Prior to the availability of fully controllable power switches, thyristors were the major power devices used in power electronic circuits. The resonant switch is said to operate in half-wave mode. If a diode is connected in anti-parallel with the unidirectional switch, the switch current can flow in both directions. Quasi-resonant converters (QRCs) can be considered as a hybrid of resonant and PWM converters. The underlying principle is to replace the power switch in PWM converters with the resonant switch. Zero-current switching (ZCS) can eliminate the switching losses at turn offand reduce the switching losses at turn on. As a relatively large capacitor is connected across the output diode during resonance, the converter operation becomes insensitive to the diode's junction capacitance. Resonant dc link inverter with low voltage stress consists of a front-end resonant converter that can pull the dc link voltage down just before any inverter switching. This resonant dc circuit serves as an interface between the dc power supply and the inverter. © 2011 Elsevier Inc. All rights reserved.
  • Journal article
    Talj R, Ortega R, Astolfi A, 2011,

    Passivity and robust PI control of the air supply system of a PEM fuel cell model

    , AUTOMATICA, Vol: 47, Pages: 2554-2561, ISSN: 0005-1098
  • Journal article
    Amrit R, Rawlings JB, Angeli D, 2011,

    Economic optimization using model predictive control with a terminal cost

    , ANNUAL REVIEWS IN CONTROL, Vol: 35, Pages: 178-186, ISSN: 1367-5788
  • Journal article
    Kokotovic PV, Astolfi A, 2011,

    David Mayne: Half a century of creativity

    , ANNUAL REVIEWS IN CONTROL, Vol: 35, Pages: 149-152, ISSN: 1367-5788
  • Journal article
    Junyent-Ferre A, Gomis-Bellmunt O, Green TC, Soto-Sanchez DEet al., 2011,

    Current Control Reference Calculation Issues for the Operation of Renewable Source Grid Interface VSCs Under Unbalanced Voltage Sags

    , IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 26, Pages: 3744-3753, ISSN: 0885-8993
  • Journal article
    He C, Kiziroglou ME, Yates DC, 2011,

    A MEMS Self-Powered Sensor and RF Transmission Platform for WSN Nodes

    , IEEE Sensors Journal, Vol: 11, Pages: 3437-3445
  • Journal article
    Mitcheson PD, Toh TT, Wong KH, Burrow SG, Holmes ASet al., 2011,

    Tuning the Resonant Frequency and Damping of an Electromagnetic Energy Harvester Using Power Electronics

    , IEEE Transactions on Circuits and Systems. Part 2: Express Briefs, Vol: 58, Pages: 792-796
  • Journal article
    Longo S, Kerrigan EC, Ling KV, Constantinides GAet al., 2011,

    A parallel formulation for predictive control with nonuniform hold constraints

    , Annual Reviews in Control, Vol: 35, Pages: 207-214, ISSN: 1872-9088

    This paper investigates the use of parallel computing architectures (multi-core, FPGA, GPU) to solve, at each sampling instant, a constrained optimal control problem. A set of approximated (hence smaller) problems are solved simultaneously and the solution of the one with lower open-loop cost is implemented. The approximation consists of the inclusion of additional hold constraints, which effectively reduce the number of steps in the prediction. Since smaller problems are solved, and these are solved in parallel, the computational delay is reduced and faster sampling becomes an option. The proposed method can outperform, in terms of closed-loop cost, a standard receding horizon control formulation because higher sampling rates can improve performance, even if suboptimal solutions are considered. Feasibility and stability can be guaranteed by an appropriate selection of the hold constraints.
  • Conference paper
    Jerez JL, Kerrigan EC, Constantinides GA, 2011,

    A Condensed and Sparse QP Formulation for Predictive Control

    , IEEE Control and Decision Conference
  • Conference paper
    Dicken J, Mitcheson PD, Elliott A, Yeatman EMet al., 2011,

    Single-Supply Pre-Biasing Circuit for Low-Amplitude Energy Harvesting Applications

    , PowerMEMS 2011, Pages: 46-49

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