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  • Journal article
    Astolfi A, Kaliora G, 2005,

    A geometric characterization of feedforward forms

    , IEEE Transactions on Automatic Control, Vol: 50, Pages: 1016-1020, ISSN: 0018-9286
  • Conference paper
    Rakovic S V, Mayne D Q, 2004,

    Robust model predictive control of constrained, piecewise affine, discrete-time systems
  • Journal article
    Chan SSM, Chung HSH, Hui SYR, 2004,

    A hybrid lamp power control scheme for dimmable electronic ballast to minimize ambient temperature effect

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 3, Pages: 1792-1798, ISSN: 0275-9306

    A hybrid lamp power control scheme for dimmable electronic ballast is proposed. Apart from adjusting the brightness of the lamp, the proposed method can also minimize the ambient temperature effect on affecting the light output. Instead of regulating the lamp current, the proposed method is based on regulating the power supplying to the lamp. First dimming operation is achieved by regulating the dc voltage at the ballast inverter input. Second variation of the lamp power (due to the temperature effect) is regulated by sensing the inverter average input current to adjust the switching frequency of the inverter. An 18W prototype has been built and tested. The lamp power and luminous output of the prototype at the ambient temperature from 5°C to 35°C have been studied.
  • Journal article
    Lee STS, Chung HSH, Hui SYR, 2004,

    TRIAC dimmable electronic ballast with lamp power equalization

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 3, Pages: 1754-1760, ISSN: 0275-9306

    A two-stage, two-wire TRIAC dimmable electronic ballast for fluorescent lamps is presented in this paper. It is constructed by using a flyback converter as the input power factor corrector to supply a half-bridge series-resonant parallel-loaded inverter to ballast the lamp. The flyback converter is operated in discontinuous conduction mode so that the filtered input current profile is same as the TRIAC-controlled voltage waveform. The switches in the inverter are switched at a constant frequency slightly higher than the resonant frequency of the resonant tank. Based on the constant average input current characteristics of the inverter, dimming operation is simply achieved by pulse-width-modulation control of the magnitude of the flyback converter output voltage. No synchronization network is required between the input and output stages. In addition, a novel power equalization scheme is developed so that the dc link voltage (and hence the lamp power) is in linear relationships with the firing angle of the TRIAC. The average output voltage of the dimmer controls the equalized flyback converter output voltage. Modeling, analysis, and design of the ballast will be described. A prototype has been implemented to verify the experimental measurements with the theoretical predictions.
  • Journal article
    Chan SSM, Chung HSH, Hui SYR, 2004,

    An IC-less dimmable electronic ballast for fluorescent lamps

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 3, Pages: 1772-1778, ISSN: 0275-9306

    This paper presents a low-cost solution of converting the popularly adopted non-dimmable electronic ballast circuit for fluorescent lamps with self-oscillating series resonant inverter into a dimmable one. Dimming function is achieved by increasing the switching frequency of the inverter from the natural frequency of the resonant tank, so that less energy is coupled to the lamp. Control of the switching frequency is based on deriving an adjustable dc current source from the resonant inductor in the resonant tank to control the operating point of the saturable transformers for driving the switches in the inverter. The overall implementation does not require any integrated circuit. A 17W prototype has been built and studied. Theoretical predictions have been verified with experimental results. The lamp can be dimmed down to 10% of the full brightness.
  • Journal article
    Hui SYR, Ho WC, 2004,

    A new generation of universal contactless battery charging platform for portable consumer electronic equipment

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 1, Pages: 638-644, ISSN: 0275-9306

    This invention is related to a new planar inductive battery charger for portable electronic equipment such as mobile phones, palm pilots and CD players. New multi-layer printed-circuit-board (PCB) winding matrices of hexagonal structures that can generate magnetic flux of almost even magnitude over the surface of the winding arrays have been developed. The new concept forms the basis for a new generation of universal charging platform for a wide range of portable electronic equipment. Different types of portable electronic equipment can be placed and charged simultaneously on the charging platform, regardless of their positions and orientation. The principle and structure of the charging platform are explained and the feasibility has been confirmed with practical measurements. The proposed universal charging platform has been successfully used for mobile phones, MP3 players and electronic dictionaries.
  • Journal article
    Qiu D, Hui SYR, Chung H, 2004,

    A nonlinear compensation scheme for a non-dissipative single-sensor parameter monitoring method used in power electronics systems

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 2, Pages: 1581-1586, ISSN: 0275-9306

    A non-dissipative single-sensor measurement technique has been proposed as a new and effective sensing technique for power electronic systems. By using only one current sensor to sense the inductor current, the proposed technique can provide all necessary information for feedforward and feedback control and parameter monitoring. In this paper, this technique is extended to a nonlinear compensation scheme taking inductor's magnetic saturation into account. A practical compensation scheme has been successfully implemented. Practical details for the circuit implementation of the nonlinear compensation scheme is included and explained. Measurements have confirmed that the compensation scheme provides more accurate estimated results than the standard scheme when the converter inductor gets into the nonlinear region.
  • Journal article
    Lee STS, Chung HSH, Hui SY, 2004,

    Use of saturable inductor to improve the dimming characteristics of frequency-controlled dimmable electronic ballasts

    , IEEE Transactions on Power Electronics, Vol: 19, Pages: 1653-1660, ISSN: 0885-8993

    This paper presents an investigation into the use of saturable inductor to improve the dimming characteristics of frequency-controlled dimmable electronic ballasts with a half-bridge series-resonant parallel-loaded inverter. The concept is based on the fact that the effective resonant frequency increases as the inductor current increases, if the unsaturable inductor in the resonant tank circuit is replaced with a saturable one. Susceptibility of the lamp power to the switching frequency variation at low luminous level can be reduced. This can lessen the problem of lamp flickers at dimmed level and result in a wider dimming range and improved controllability. The method gives a simple solution of improving the dimming characteristics without changing the circuit structure. A fundamental frequency model that includes the characteristics of the nonlinear lamp resistance and filament resistance is applied in the analysis. A PSIM simulation model for the saturable inductor is developed. Theoretical predictions are verified with the experimental results of a 36-W T8 prototype. © 2004 IEEE.
  • Journal article
    Yan W, Hui SY, 2004,

    An improved high-intensity discharge lamp model including acoustic resonant effect on the lamp arc resistance

    , IEEE Transactions on Power Electronics, Vol: 19, Pages: 1661-1667, ISSN: 0885-8993

    An improved physical high-intensity discharge lamp model that combines the concept of acoustic resonance prediction based on the geometric structure of the lamp, energy balance equations, and lamp arc resistance modeling is proposed. It can be incorporated into a PSpice model for prediction of lamp voltage and current under both low and high frequency operations. In particular, variation of lamp arc resistance due to acoustic resonance at high-frequency operation is incorporated into the model. The validity of the model has been confirmed with measurements. © 2004 IEEE.
  • Journal article
    Chaudhuri B, Majumder R, Pal BC, 2004,

    Wide-area measurement-based stabilizing control of power system considering signal transmission delay

    , IEEE TRANSACTIONS ON POWER SYSTEMS, Vol: 19, Pages: 1971-1979, ISSN: 0885-8950
  • Journal article
    Kaliora G, Astolfi A, 2004,

    Nonlinear control of feedforward systems with bounded signals

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 49, Pages: 1975-1990, ISSN: 0018-9286
  • Journal article
    Yan W, Hui SYR, 2004,

    The investigation on the starting process inside a small wattage metal halide lamps and its influence on extra high frequency ballast circuit design

    , Institute of Physics Conference Series, Vol: 182, Pages: 291-292, ISSN: 0951-3248

    The starting process of a small wattage MH lamp and its influence on the high frequency ballast circuit design, were investigated. A HID lamp follows the procedure of breakdown, mercury vapor arc, glow, glow-to-arc transition, thermionic low pressure arc and fully developed arc. The starting procedure of small wattage MH lamp is dominated by mercury vapor arc at 50 Mz. Further, at extra high frequency, the process is dominated by glow discharge and has a faster glow-to-arc transition.
  • Journal article
    Sharp RS, Evangelou S, Limebeer DJN, 2004,

    Advances in the modelling of motorcycle dynamics

    , MULTIBODY SYSTEM DYNAMICS, Vol: 12, Pages: 251-283, ISSN: 1384-5640
  • Journal article
    Astolfi A, Colaneri P, 2004,

    A note on the existence of positive realizations

    , LINEAR ALGEBRA AND ITS APPLICATIONS, Vol: 390, Pages: 329-343, ISSN: 0024-3795
  • Journal article
    Chaudhuri B, Majumder R, Pal BC, 2004,

    Application of multiple-model adaptive control strategy for robust damping of interarea oscillations in power system

    , IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, Vol: 12, Pages: 727-736, ISSN: 1063-6536
  • Journal article
    Chan SSM, Chung HSH, Hui RSY, 2004,

    Self-oscillating dimmable electronic ballast for fluorescent lamps

    , IEEE Power Electronics Letters, Vol: 2, Pages: 87-91, ISSN: 1540-7985

    This letter presents a low-cost solution for converting the popularly adopted nondimmable electronic ballast circuit for fluorescent lamps with self-oscillating series resonant inverter into a dimmable one. The dimming function is achieved by increasing the switching frequency of the inverter from the natural frequency of the resonant tank, so that less energy is coupled to the lamp. Control of the switching frequency is based on deriving an adjustable dc current source from the inductor in the resonant tank to control the operating point of the saturable chokes for driving the switches in the inverter. The overall circuit does not require any integrated circuit. A 17-W prototype has been built and tested. Theoretical predictions have been verified with experimental results. The lamp can be dimmed to 10% of the full brightness.
  • Book
    Kirschen D, Strbac G, 2004,

    Fundamentals of Power System Economics
  • Journal article
    Lovera M, Astolfi A, 2004,

    Spacecraft attitude control using magnetic actuators

    , AUTOMATICA, Vol: 40, Pages: 1405-1414, ISSN: 0005-1098
  • Journal article
    Yip SC, Chung HSH, Hui SYR, Chiu YCet al., 2004,

    Modeling, analysis and design of a thyristor-based BI-directional ac-dc converter

    , Journal of Circuits, Systems and Computers, Vol: 13, Pages: 687-705, ISSN: 0218-1266

    This paper presents the modeling, analysis, and design of a thyristor-based ac-dc converter, featuring bi-directional power flow and unity power factor at the ac side in both powering and regenerating modes. By applying the y-parameter modeling technique and eliminating the effects of the high-frequency poles and zeros, small-signal models of the converter in both modes and a unified controller have been developed. The controller regulates the voltage at the dc side and operates as a. feedback controller in the powering mode and a feedforward controller in the regenerating mode. Systematic procedures for determining the circuit component values of the power conversion stage and the controller are presented. The operation is illustrated with the design of a 500-W, 100-V (ac)/200-V (dc) prototype, supplying to a motor-generator set. Experimental results showing operation in the powering mode, regenerating mode, and during mode changeover are included. Circuit operations during the transient of the changeover operation are clearly identified. © World Scientific Publishing Company.
  • Journal article
    Zhang XD, Parisini T, Polycarpou MM, 2004,

    Adaptive fault-tolerant control of nonlinear uncertain systems: An information-based diagnostic approach

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 49, Pages: 1259-1274, ISSN: 0018-9286
  • Journal article
    Angeli D, Sontag ED, De Leenheer P, 2004,

    A small-gain theorem for almost global convergence of monotone systems

    , Systems and Control Letters, Vol: 52, Pages: 407-414, ISSN: 0167-6911
  • Journal article
    Vinter RB, Clark JMC, James MR, 2004,

    The Interpretation of Discontinuous State Feedback Control Laws as Non-Anticipative Control Strategies in Differential Games

    , IEEE Transactions Automatic Control, Vol: 49, Pages: 1360-1365
  • Journal article
    Yates DC, Holmes AS, Burdett AJ, 2004,

    Optimal transmission frequency for ultralow-power short-range radio links

    , IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS, Vol: 51, Pages: 1405-1413, ISSN: 1549-8328
  • Conference paper
    Rakovic SV, Kerrigan EC, Mayne DQ, 2004,

    Optimal control of constrained piecewise affine systems with state- and input-dependent disturbances
  • Journal article
    Angeli D, Ingalls B, Sontag ED, Wang Yet al., 2004,

    Uniform global asymptotic stability of differential inclusions

    , JOURNAL OF DYNAMICAL AND CONTROL SYSTEMS, Vol: 10, Pages: 391-412, ISSN: 1079-2724
  • Conference paper
    Rakovic SV, Kerrigan EC, Mayne DQ, 2004,

    Optimal control of constrained piecewise affine systems with state- and input-dependent disturbances
  • Journal article
    Mitcheson PD, Green TC, Yeatman EM, Holmes ASet al., 2004,

    Architectures for vibration-driven micropower generators

    , JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, Vol: 13, Pages: 429-440, ISSN: 1057-7157
  • Book chapter
    Clark JMC, Vinter RB, 2004,

    On the interpretation of non-anticipative control strategies in differential games and applications to flow control

    , Optimal control, stabilization and nonsmooth analysis, Editors: De Queiroz, Malisoff, Wolenski, Berlin, Publisher: Springer, Pages: 29-48, ISBN: 9783540213307
  • Journal article
    Angeli D, 2004,

    An almost global notion of input-to-state stability

    , IEEE Trans. on Automatic Control, Vol: 49, Pages: 866-874, ISSN: 0018-9286
  • Journal article
    Ho BMT, Chung HSH, Hui SYR, 2004,

    An integrated inverter with maximum power tracking for grid-connected PV systems

    , Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, Vol: 3, Pages: 1559-1565

    An inverter for grid-connected photovoltaic systems is presented in this paper. It can globally locate the maximum power point of the panel over wide insolation and feed the solar energy to the grid. Its structure mainly integrates a previously developed maximum point tracking method and output current shaping function into a buck-boost-derived converter and then inverts the shaped current through a grid frequency bridge to the grid. Instead of having a storage capacitor connecting in parallel with the converter output, series connection is used, so that the required capacitor voltage rating is lower than that in classical inverters. Most importantly, the inverter output current harmonics are less sensitive to the capacitor value. A 30W laboratory prototype has been built. The tracking capability, inversion efficiency, and large-signal responses at different insolations have been investigated. Detailed analysis on the inverter performance has been performed. The theoretical predictions are verified with the experimental results.

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