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  • Conference paper
    Costa EF, Astolfi A, 2008,

    On the stability of the recursive Kalman filter for linear time-invariant systems

    , American Control Conference 2008, Publisher: IEEE, Pages: 1286-1291, ISSN: 0743-1619
  • Conference paper
    Mei F, Pal BC, 2008,

    Modelling of doubly-fed induction generator for power system stability study

    , General Meeting of the IEEE-Power-and-Energy-Society, Publisher: IEEE, Pages: 287-294, ISSN: 1944-9925
  • Journal article
    Back J, Astolfi A, 2008,

    Design of positive linear observers for positive linear systems via coordinate transformations and positive realizations

    , SIAM JOURNAL ON CONTROL AND OPTIMIZATION, Vol: 47, Pages: 345-373, ISSN: 0363-0129
  • Conference paper
    Soto D, Pena R, Wheeler P, Green TCet al., 2008,

    Regulation of the Capacitor Voltages in a Direct-like Cascade AC-AC Converter for FACTS Controllers

    , 39th IEEE Power Electronics Specialists Conference (PESC 08), Publisher: IEEE, Pages: 4110-+, ISSN: 0275-9306
  • Conference paper
    Casson AJ, Yates DC, Patel S, Rodriguez-Villegas Eet al., 2007,

    Algorithm for AEEG data selection leading to wireless and long term epilepsy monitoring

    , Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE, Pages: 2456-2459, ISSN: 1557-170X
  • Journal article
    Chan PKW, Chung HSH, Hui SYR, 2007,

    Generalized theory of boundary control for single-phase multilevel inverter using second-order switching surface

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Pages: 1733-1739, ISSN: 0275-9306

    The concept and derivation of second-order switching surface in boundary control is extended to multilevel inverters in this paper. The second-order switching surface is set close to the trajectory that passing through the target operating point, which accelerates the trajectory moving towards the target operating point after a hypothesized switching action. Three topologies of single-phase multilevel inverters are investigated in this paper; they are full-bridge three-level diode-clamped inverter, cascaded five-level inverter and hybrid seven-level inverter. The second-order switching surface is derived in each voltage region, and the controller is verified with circuit simulations as well as low-power prototypes. The dynamic responses of the three inverters with different loads, including resistive load, inductive load and nonlinear load are examined. The simulation and experimental results show that the output voltage of the multilevel inverters using the proposed boundary controller can achieve a near optimal response to a large-signal load disturbance and an output reference voltage change. © 2007 IEEE.
  • Journal article
    Tam PW, Chung HSH, Hui SYR, 2007,

    Iterative behavioral modeling of charge-pump based electronic ballast-fluorescent lamp system

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Pages: 2279-2286, ISSN: 0275-9306

    A new behavioral model for analyzing the charge-pump based ballast is proposed in this paper. A detailed model derivation is presented and the model is applied to analyze a ballast system of a 16W compact fluorescent lamp (CFL) as an illustration. The ballast of the CFL consists of a self-oscillatory driven inverter stage and a charge-pump circuitry. It is shown that the model can give a comprehensive interpretation of the whole system and provide a reasonable prediction of the ballast behavior. © 2007 IEEE.
  • Journal article
    Liu X, Lee CK, Hui SY, 2007,

    An integrated planar EMI filter for ultra-high frequency power converters

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Pages: 1528-1534, ISSN: 0275-9306

    In this paper, we propose an integrated planar electromagnetic interference (EMI) filter for ultra-high frequency power converters switching at or above 10MHz. The integrated planar EMI filter structure consists of coreless planar spiral windings (CPSW) and parallel copper plates. The entire structure includes both the differential-mode (DM) and common-mode (CM) filters and can be fabricated in a single multilayer printed circuit board. The CPSW is firstly characterized by a lumped high-frequency circuit model which is then extended to form the equivalent circuit of the EMI filter. The performance of the differential-mode (DM) and common-mode (CM) filters is investigated individually and then they are combined to form a planar EMI filter which can handle the DM and CM noise simultaneously. Simulated and measured results are included and they confirm the filtering effectiveness of the integrated planar EMI filter. © 2007 IEEE.
  • Journal article
    Hui SY, Chung HSH, 2007,

    Resonant and soft-switching converters

    , Pages: 405-449

    This chapter deals with resonant and soft-switching converters. Power switches cut off the load current within the turn-on and turn-off times under the hard switching conditions. Hard switching refers to the stressful switching behavior of the power electronic devices. During the turn-on and turn-off processes, the power device has to withstand high voltage and current simultaneously, resulting in high switching losses and stress. Dissipative passive snubbers are usually added to the power circuits so that the dv/dt and di/dt of the power devices could be reduced, and the switching loss and stress be diverted to the passive snubber circuits. This chapter describes the basic technology of resonant and soft-switching converters. Various forms of soft-switching techniques such as ZVS, ZCS, voltage clamping, zero-voltage transition methods, etc. are addressed. The emphasis is placed on the basic operating principle and practicality of the converters without using much mathematical analysis. © 2007 Elsevier Inc. All rights reserved.
  • Journal article
    Su YP, Liu X, Hui SY, 2007,

    Extended theory on the inductance calculation of planar spiral windings including the effect of double-layer electromagnetic shield

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Pages: 3022-3028, ISSN: 0275-9306

    Recent progress on wireless planar battery charging platform highlights a requirement that the platform must be shielded underneath so that the electromagnetic (EM) flux will not leak through the bottom of the charging platform. The presence of the EM shield will inevitably alter the flux distribution and thus the inductance of the planar windings. In this paper, a theory of calculating inductance of spiral windings is extended to determine the inductance of planar spiral windings shielded by a double-layer planar EM shield. With the generalized equations, the impedance of the planar spiral windings on double-layer shielding substrate and the optimal thickness of shielding materials can be calculated accurately without using time-consuming finite-element method. Therefore, the influence of the double-layer electromagnetic shield on the inductance of the planar spiral windings can be analyzed. Simulations and measurements have been carried out for several shielding plates with different permeability, conductivity and thickness. Both of the simulations and measurements of the winding inductance agree well with the extended theory. © 2007 IEEE.
  • Journal article
    Chung HSH, Ho NM, Yan W, Tam PW, Hui SYet al., 2007,

    Comparison of dimmable electromagnetic and electronic ballast systems - An assessment on energy efficiency and lifetime

    , IEEE Transactions on Industrial Electronics, Vol: 54, Pages: 3145-3154, ISSN: 0278-0046

    There is a common misconception that energy saving is always equivalent to environmental protection. Compared with electromagnetic ballasts, electronic ballasts have a much shorter lifetime and are not recyclable. This prompts new concerns about their environmental impacts due to the accumulation of a huge amount of toxic and/or nonbiodegradable electronic waste components and materials. In this paper, the combined use of a central dimming system with low-loss electromagnetic ballasts is compared with electronic ballasts. Experimental results have confirmed that the use of a central dimming system for large electromagnetic-ballast-driven lighting systems can be as energy efficient as electronic ballasts. Considering the long lifetime (> 30 years) of electromagnetic ballasts and the recyclability of their magnetic chokes, this paper shows that such combined technology can provide an improved environmentally friendly and energy-saving solution for large-scale electric-lighting systems, particularly for lighting systems in large public areas. Due to the elimination of many electronic ballasts, this proposed technology has the potential of drastically reducing a huge amount of electronic waste. With the positive results obtained in this paper, it is hoped that international regulatory organizations would reconsider their current policies and promote lighting technology that is both environmentally friendly and energy saving. © 2007 IEEE.
  • Conference paper
    Chang H, Astolfi A, 2007,

    Immune Response’s Enhancement via Controlled Drug Scheduling

    , Pages: 3919-3924
  • Conference paper
    Tanelli M, Osorio G, di Bernardo M, Savaresi SM, Astolfi Aet al., 2007,

    Limit Cycles Analysis in Hybrid Anti-lock Braking Systems

    , Pages: 3865-3870
  • Conference paper
    Astolfi A, 2007,

    Asymptotic tracking of a state trajectory by output-feedback for a class of non linear systems

    , Pages: 5228-5233
  • Conference paper
    Yeatman EM, Mitcheson PD, Holmes AS, 2007,

    Micro-Engineered Devices for Motion Energy Harvesting

    , 2007 IEEE International Electron Devices Meeting, Pages: 375-378
  • Conference paper
    Astolfi A, 2007,

    A new look at model reduction by moment matching for linear systems

    , Pages: 4366-4361
  • Conference paper
    Karagiannis D, Carnevale D, Astolfi A, 2007,

    Output feedback stabilisation of a class of nonlinear systems via reduced-order observers and certainty equivalence

    , Pages: 402-407
  • Conference paper
    Frangos M, Jaimoukha IM, 2007,

    Adaptive model reduction of large scale systems : A practical rational Arnoldi algorithm

    , Pages: 4379-4384
  • Journal article
    Tigan G, Astolfi A, 2007,

    A note on a piecewise-linear duffing-type system

    , INTERNATIONAL JOURNAL OF BIFURCATION AND CHAOS, Vol: 17, Pages: 4425-4429, ISSN: 0218-1274
  • Conference paper
    Orukpe PE, Jaimoukha IM, 2007,

    A semidefinite relaxation for the quadratic minimax problem in H-infinity model predictive control

    , Pages: 117-181
  • Journal article
    De Leenheer P, Sontag ED, Angeli D, 2007,

    A Petri Net approach to the study of persistence in chemical reaction networks

    , Mathematical Biosciences, Vol: 210, Pages: 598-618, ISSN: 0025-5564
  • Journal article
    Chan PCF, Lee CK, Hui SYR, 2007,

    Stray capacitance calculation of coreless planar transformers including fringing effects

    , Electronics Letters, Vol: 43, Pages: 1308-1309, ISSN: 0013-5194

    An accurate method for calculating the capacitance between parallel spiral planar windings including fringing effects is proposed. The capacitance equation provides a fast numerical tool for capacitance calculation of planar coreless transformers. Practical measurements match well with the theoretical calculations for a range of samples. © The Institution of Engineering and Technology 2007.
  • Journal article
    Yan W, Tam E, Hui SY, 2007,

    A semi-theoretical fluorescent lamp model for time-domain transient and steady-state simulations

    , IEEE Transactions on Power Electronics, Vol: 22, Pages: 2106-2115, ISSN: 0885-8993

    Low-pressure discharge lamps obey a set of physical laws that are different from those of high-pressure discharge lamps. In this paper, these differences are addressed. Based on a recently developed HID lamp model frame, a semi-theoretical fluorescent lamp model that can be determined by genetic algorithms and simple electrical measurements is presented. This model does not require any lamp data from lamp manufacturers. Its parameters can be determined from electrical voltage and current measurements of the lamps under ac operation at mains frequency. With the same set of parameters, the model can predict the lamp terminal characteristics accurately under low, medium and high frequency operations. Good simulation results were achieved when the lamp power was reduced to 60% of rated power and when the lamp was operated under step-up and step-down transient processes. Simulation results for different sizes of tubular and compact fluorescent lamps agree well with their experimental results. Particularly, the differences between simulation results and experimental results under rated power are less than 10%. Hence, the proposed model shows a good degree of accuracy: 1) for different types of fluorescent lamps; 2) at different operating frequencies; 3) under different dimming levels; and 4) during step-up and step-down transient processes. © 2007 IEEE.
  • Conference paper
    Toh TT, Bansal A, Hong G, Mitcheson PD, Holmes AS, Yeatman EMet al., 2007,

    Energy Harvesting From Rotating Structures

    , PowerMEMS 2007, Pages: 327-330
  • Journal article
    Lu HY, Zhu JG, Hui SYR, 2007,

    Measurement and modeling of thermal effects on magnetic hysteresis of soft ferrites

    , IEEE Transactions on Magnetics, Vol: 43, Pages: 3952-3960, ISSN: 0018-9464

    We present experimental measurement of thermal effects on magnetic hysteresis of soft ferrite cores commonly used in high-frequency inductors and transformers and propose a method to model the thermal effects. We measured the major hysteresis loops of soft ferrite core samples from various vendors at different temperatures, and found that the saturation points of the limiting hysteresis loops vary with the temperature substantially in a nonlinear manner, but within the normal operating temperature range, typically 20degC-100degC, this variation can be approximately regarded as linear with an acceptable error. We propose a simple method based on this approximation for determining the limiting hysteresis loop of a soft ferrite for a given temperature. This method is validated by the substantial agreement between the experimental measurement and simulation by the scalar Preisach hysteresis model of major hysteresis loops of the test samples at different temperatures. Since most manufacturers provide the limiting loops of their soft ferrite cores at two typical temperatures, the proposed method is very convenient for engineering applications. © 2007 IEEE.
  • Journal article
    Liu X, Hui SY, 2007,

    Simulation study and experimental verification of a universal contactless battery charging platform with localized charging features

    , IEEE Transactions on Power Electronics, Vol: 22, Pages: 2202-2210, ISSN: 0885-8993

    This paper presents a finite-element (FE) simulation study of a planar contactless battery charging platform for portable consumer electronic equipment. Magnetic field plots of the charging platform are generated under no-load and loaded conditions so that the field distribution of the planar charging platform can be visualized. Three working modes of the platform have been investigated and compared, including full excitation and two forms of selective excitation. With new results arising from this FE simulation study and practical experiments, the theory of the magnetomotive force (mmf) generation of the multilayer planar printed-circuit-board winding array structure can be further understood. The results obtained in this paper provide a foundation of understanding for future design and optimization of planar contactless charging platforms. In addition, it has been confirmed that an electromagnetic shield structure that has been applied to coreless planar transformer applications, can work equally well for the planar charging platform. © 2007 IEEE.
  • Conference paper
    Rehman Shaikh MA, Mitcheson PD, Green TC, 2007,

    Power Loss Minimisation in Multilevel Converters for Distribution Networks

    , IEEE IECON, Pages: 1774-1779
  • Conference paper
    Gandu KR, Green TC, Mitcheson PD, 2007,

    Simulation toolkit for energy scavenging inertial micro power generators

    , Pages: 137-140
  • Conference paper
    Rehman Shaikh MA, Mitcheson PD, Green TC, 2007,

    Power Loss Minimisation in Multilevel Converters for Distribution Networks

    , IEEE IECON, Pages: 1774-1779
  • Journal article
    Norheim I, Pudjianto D, 2008,

    Method for assessing impact of large-scale wind power integration on reserves

    , WIND ENERGY, Vol: 11, Pages: 85-96, ISSN: 1095-4244

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