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  • Journal article
    Tang SC, Hui SYR, Chung HSH, 2001,

    A low-profile wide-band three-port isolation amplifier with coreless printed-circuit-board (PCB) transformers

    , IEEE Transactions on Industrial Electronics, Vol: 48, Pages: 1180-1187, ISSN: 0278-0046

    Galvanic isolations are essential in many electrical patient-monitoring devices and industrial applications. In this paper, a low-profile wideband three-port isolation amplifier using coreless printed-circuit-board (PCB) transformers for isolation is studied. The PCB thickness used in the isolation amplifier is 0.4 mm. The diameters of the two coreless PCB transformers are 9.75 and 5.856 mm, respectively. Operating conditions of the transformers and a design guideline of the isolation amplifier are detailed in this paper. Experimental results show that the isolation amplifier under investigation can transmit an analog signal from 20 mHz to 1.1 MHz with good linearity. Comparison of the prototype with an industrial isolation amplifier is also included.
  • Journal article
    Alessandri A, Parisini T, Zoppoli R, 2001,

    Sliding-window neural state estimation in a power plant heater line

    , INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Vol: 15, Pages: 815-836, ISSN: 0890-6327
  • Journal article
    Strbac G, Allan R, 2001,

    Performance regulation of distribution systems using reference networks

    , Power Engineering Journal, Vol: 15, Pages: 295-303
  • Journal article
    Astolfi A, Colaneri P, 2001,

    Trading robustness with optimality in nonlinear control

    , AUTOMATICA, Vol: 37, Pages: 1961-1969, ISSN: 0005-1098
  • Journal article
    Hussain MA, Ho PY, Allwright JC, 2001,

    Adaptive linearizing control with neural-network-based hybrid models

    , INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 40, Pages: 5604-5620, ISSN: 0888-5885
  • Journal article
    Ho YKE, Lee STS, Chung HSH, Hui SYet al., 2001,

    A comparative study on dimming control methods for electronic ballasts

    , IEEE Transactions on Power Electronics, Vol: 16, Pages: 828-836, ISSN: 0885-8993

    A comparative study on the performance characteristics between the variable switching frequency scheme (VFS) and variable voltage scheme (VVS) was carried out. By using the fundamental-frequency model and the nonlinear lamp resistance characteristics, the steady state solution and starting voltage characteristics were derived. It was shown that the VVS has several operational advantages over the VFS in dimming operation.
  • Journal article
    Zhang J, Chung HSH, Lo WL, Hui SY, Wu AKMet al., 2001,

    Implementation of a decoupled optimization technique for design of switching regulators using genetic algorithms

    , IEEE Transactions on Power Electronics, Vol: 16, Pages: 752-763, ISSN: 0885-8993

    This paper presents an implementation of a decoupled optimization technique for design of switching regulators using genetic algorithms (GAs). The optimization process entails the selection of component values in a switching regulator, in order to meet the static and dynamic requirements. Although the proposed method inherits characteristics of evolutionary computations that involve randomness, recombination, and survival of the fittest, it does not perform a whole-circuit optimization. Thus, intensive computations that are usually found in stochastic optimization techniques can be avoided. Similar to many design approaches for power electronics circuits, a regulator is decoupled into two components, namely the power conversion stage (PCS) and the feedback network (FN). The PCS is optimized with the required static characteristics, whilst the FN is optimized with the required static and dynamic behaviors of the whole system. Systematic optimization procedures will be described and the technique is illustrated with the design of a buck regulator with overcurrent protection. The predicted results are compared with the published results available in the literature and are verified with experimental measurements.
  • Journal article
    Curcic S, Strbac G, Zhang XP, 2001,

    Effect of losses in design of distribution circuits

    , Generation, Transmission and Distribution, IEE Proceedings, Vol: 148, Pages: 632-642, ISSN: 1350-2360
  • Journal article
    Yip SC, Qiu DY, Chung HSH, Hui SYRet al., 2001,

    A novel voltage sensorless control technique for a bidirectional ac/dc converter

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 4, Pages: 1899-1904, ISSN: 0275-9306

    A novel voltage sensorless control technique for a bidirectional ac/dc converter is presented. Only a single current sensor that measures the inductor current is needed in the whole system. The sensed inductor current is used for two functions. The first one is for shaping the current waveform at the ac side and the second one is for deriving the inductor voltage by determining the rate of change of the inductor current. The ac- and dc-side voltages, which are used for ac current synchronization and dc voltage regulation, respectively, are obtained by extracting the envelopes of the derived inductor voltage. Apart from reducing the number of sensing elements, the proposed method has additional advantages of 1) providing inherent electrical isolation and reducing noise coupling between the power circuit and the controller, and 2) having wide operating range. Design criteria for the differentiator and envelope detector circuit will be described. The applicability of the proposed method is verified with the experimental results of a prototype.
  • Journal article
    Tse KK, Chung HSH, Hui SYR, Ho MTet al., 2001,

    A novel maximum power point tracking technique for PV panels

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 4, Pages: 1970-1975, ISSN: 0275-9306

    A novel technique for efficiently extracting maximum power from photovoltaic (PV) panels is presented. The power conversion stage, which is connected between a PV panel and a load or bus, is a SEPIC or Cuk dc/dc converter operating in discontinuous inductor-current or capacitor-voltage mode. The method of locating the maximum power point (MPP) is based on injecting a small-signal sinusoidal perturbation into the switching frequency and comparing the ac component and the average value of the panel terminal voltage. Apart from not requiring any sophisticated digital computation of the panel power, the proposed technique does not approximate the panel characteristics and can globally locate the MPP under wide insolation conditions. The tracking capability has been verified experimentally with a 10W solar panel under a controlled experimental setup. Performances under different insolation levels and a large insolation level change will be studied.
  • Journal article
    Cao X, Yan W, Hui SYR, Chung HSHet al., 2001,

    High-frequency modeling of low-wattage high-intensity-discharge (HID) lamps

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 1, Pages: 62-66, ISSN: 0275-9306

    The prediction of acoustic resonance frequency distribution and modeling of small wattage metal-halide (MH) lamp was discussed. The acoustic resonance frequencies scattered over a broad frequency band were predicted by simplified acoustic wave equation. The mathematical model was used as general-purpose CAD tool for simulating high-frequency behavior of low-wattage high intensity discharge (HID) lamps. This approach provided tool for electronic ballast designers to predict the unstable frequency regions of HID lamps and to design control for the ballast.
  • Journal article
    Soto-Sanchez DE, Green TC, 2001,

    Voltage balance and control in a multi-level unified power flow controller

    , IEEE TRANSACTIONS ON POWER DELIVERY, Vol: 16, Pages: 732-738, ISSN: 0885-8977
  • Journal article
    Yan W, Ho YKE, Hui SYR, 2001,

    Stability study and control methods for small-wattage high-intensity-discharge (HID) lamps

    , IEEE Transactions on Industry Applications, Vol: 37, Pages: 1522-1530, ISSN: 0093-9994

    The increasing speed of modern power electronics opens a way to study the stability of high-intensity-discharge lamps at very-high-frequency operation. In this paper, a lamp stability study based on a simplified theory on acoustic resonance frequency distribution in a small-wattage metal-halide (MH) lamp is presented. The frequency characteristic of a low-wattage MH lamp has been analyzed. Up to 700 kHz, extensive experiments using resonant-type electronic ballast have been conducted on 35-W MH lamps to investigate different control methods for avoiding acoustic resonance. The results indicate that a randomized switching scheme cannot always eliminate arc instabilities caused by acoustic resonances in small-wattage MH lamps. The stability frequency regions should be identified. A stable arc can be obtained when the lamp is operated above the highest acoustic resonance frequency.
  • Journal article
    Vellekoop MH, Clark JMC, 2001,

    Optimal speed of detection in generalized Wiener disorder problems

    , Stochastic Processes and their Applications, Vol: 95, Pages: 25-54
  • Journal article
    El-Zobaidi HMH, Jaimoukha IM, Limebeer DJN, 2001,

    Normalized <i>H</i><sub>∞</sub> controller reduction with <i>A Priori</i> error bounds

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 46, Pages: 1477-1483, ISSN: 0018-9286
  • Journal article
    Zhang XD, Polycarpou M, Parisini T, 2001,

    Robust fault isolation for a class of non-linear input-output systems

    , INTERNATIONAL JOURNAL OF CONTROL, Vol: 74, Pages: 1295-1310, ISSN: 0020-7179
  • Journal article
    Baglietto M, Parisini T, Zoppoli R, 2001,

    Numerical solutions to the Witsenhausen counterexample by approximating networks

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 46, Pages: 1471-1477, ISSN: 0018-9286
  • Journal article
    Angeli D, Nešić D, 2001,

    Power characterizations of input-to-state stability and integral input-to-state stability

    , IEEE Transactions on Automatic Control, Vol: 46, Pages: 1298-1303, ISSN: 0018-9286

    New notions of external stability for nonlinear systems are introduced, making use of average powers as signal norms and comparison functions as in the input-to-state stability (ISS) framework. Several new characterizations of ISS and integral ISS are presented in terms of the new notions. An example is discussed to illustrate differences and similarities of the newly introduced properties.
  • Journal article
    Parisini T, Sacone S, 2001,

    Stable hybrid control based on discrete-event automata and receding-horizon neural regulators

    , AUTOMATICA, Vol: 37, Pages: 1279-1292, ISSN: 0005-1098
  • Journal article
    Pal BC, Coonick AH, Cory BJ, 2001,

    Linear matrix inequality versus Root-locus approach for damping inter-area oscillations in power systems

    , INT Journal of ELECTRICAL POWER AND ENERGY SYSTEMS, Vol: 23, Pages: 481-489, ISSN: 0142-0615

    This paper describes the merits of robust damping controllers designed using a Linear Matrix Inequality (LMI) approach as compared to conventional Root-locus technique. The design in both methods aims at improving the damping of inter-area modes employing two small superconducting magnetic energy storage (SMES) devices. The LMI based control ensures adequate damping for widely varying system operating conditions and is compared with that obtained by the root-locus technique. It is shown that the LMI based approach has advantages over root-locus based control for the same control effort. (C) 2001 Elsevier Science Ltd. All rights reserved.
  • Journal article
    Angeli D, 2001,

    Almost global stabilization of the inverted pendulum via continuous state feedback

    , Automatica, Vol: 37, Pages: 1103-1108, ISSN: 0005-1098

    Continuous state feedback laws are presented for "almost" global stabilization of the planar inverted pendulum on a cart. The synthesis is carried out exploiting energy-shaping techniques and a suitable smooth switching between positive and negative feedback. Some of the employed ideas could be possibly generalized to the problem of stabilization of systems with multiple equilibrium points. © 2001 Elsevier Science Ltd.
  • Journal article
    Tang SC, Ron Hui SY, Chung HSH, 2001,

    A low-profile power converter using printed-circuit board (PCB) power transformer with ferrite polymer composite

    , IEEE Transactions on Power Electronics, Vol: 16, Pages: 493-498, ISSN: 0885-8993

    A new design of low-cost and low-profile power transformer is presented in this paper. The manufacturing cost of a power transformer can be reduced using the proposed printed-circuit board (PCB) transformer. The transformer windings are etched on the opposite sides of a double-sided PCB. Self-adhesive ferrite polymer composite (FPC) sheets are stuck on the two PCB surfaces to shield the magnetic flux induced from the transformer windings. The PCB transformer does not require manual winding and bobbin. A power converter prototype employing the PCB transformer has been implemented. The technique of choosing the optimum switching frequency of the power converter using PCB transformer is addressed in this paper. The maximum power delivered from the prototype is 94 W. The maximum efficiency of the power converter is 83.5%.
  • Journal article
    Ron Hui SY, Lee LM, Chung HSH, Ho YKet al., 2001,

    An electronic ballast with wide dimming range, high PF, and low EMI

    , IEEE Transactions on Power Electronics, Vol: 16, Pages: 465-472, ISSN: 0885-8993

    The authors describe an electronic ballast design with the capability of low radiated and conducted EMI over a wide dimming range. It overcomes some limitations of traditional electronic ballasts that use frequency variation for dimming control. The proposed design allows soft switching of the ballast from full-power operation down to less than 10% power. Low-cost and low-voltage power metal oxide semiconductor field effect transmitters (MOS-FETs) can be used in the proposed dimmable electronic ballast. The design approach is described and implemented successfully in a 2 × 36 W fluorescent lamp system.
  • Journal article
    Previdi F, Parisini T, 2001,

    Model-free fault detection: a spectral estimation approach based on coherency functions

    , INTERNATIONAL JOURNAL OF CONTROL, Vol: 74, Pages: 1107-1117, ISSN: 0020-7179
  • Journal article
    Williams P, Strbac G, 2001,

    Costing and pricing of electricity distribution services

    , Power Engineering Journal, Vol: 15, Pages: 125-136
  • Journal article
    Tang SC, Hui SY, Chung HSH, 2001,

    A low-profile low-power converter with coreless PCB isolation transformer

    , IEEE Transactions on Power Electronics, Vol: 16, Pages: 311-316, ISSN: 0885-8993

    Very small manually wound transformers for subwatt dc-dc converters are notorious for their relatively high cost and low reliability. In this paper, an isolated low-profile low-power 8 MHz soft-switching power converter using a coreless printed circuit board (PCB) transformer is described. Coreless PCB transformers eliminate several problems of their core-based counter-parts in low-power applications. The diameter of the coreless PCB transformer is merely 0.46 cm. The converter's power output is about 0.5W with a typical transformer efficiency of 63%. The high-frequency capability, high reliability and the low-profile structure make coreless PCB transformers a viable and attractive option for reliable mega-hertz switching converters and micro-circuits.
  • Journal article
    Baglietto M, Parisini T, Zoppoli R, 2001,

    Distributed-information neural control: The case of dynamic routing in traffic networks

    , IEEE TRANSACTIONS ON NEURAL NETWORKS, Vol: 12, Pages: 485-502, ISSN: 1045-9227
  • Journal article
    Chu LW, Lam KS, Tam SC, Hu WJ, Hui SL, Chiu A, Chiu KC, Ng Pet al., 2001,

    A randomized controlled trial of low-dose recombinant human growth hormone in the treatment of malnourished elderly medical patients.

    , J Clin Endocrinol Metab, Vol: 86, Pages: 1913-1920, ISSN: 0021-972X

    High-dose recombinant human GH (rhGH) has been shown to improve the nutritional status of malnourished older adults. It is uncertain whether low-dose rhGH is effective and whether its effect on nutritional status will lead to any improvement in physical function. There is also no data on the outcome after a short course of rhGH treatment. The objectives of this study were to determine the efficacy of low-dose rhGH treatment for 4 weeks in malnourished elderly patients, its effect on physical functions, and the intermediate term outcome after a 4-week rhGH treatment. The study design was a randomized, placebo-controlled, double-blind trial conducted in a university teaching hospital. The patients were 19 medically stable malnourished elderly subjects. Intervention in the rhGH group was as follows: rhGH (Saizen, Serono, Switzerland) 0.09 IU/kg body weight (BW) 3 times weekly were given together with appropriate dietary intervention as prescribed by the dietitian. In the placebo group, equal volumes of normal saline per kilogram BW were given 3 times weekly together with the dietary intervention. The baseline demographic, anthropometric, nutritional, and hematological variables, measures of physical function, and insulin-like growth factor I levels in both groups were comparable. Compared with the placebo group, the GH-treated group showed a more rapid gain in BW (after 3 weeks, +1.27 +/- 0.36 vs. -0.28 +/- 0.37 kg; P = 0.008), total lean body mass (change after 3 weeks by bio-impedance analysis, +1.45 +/- 0.36 vs. -0.37 +/- 0.48 kg; P = 0.009) and a faster improvement in 5-m walking time (decrease after 4 weeks, 23.79 +/- 9.41 vs. 0.45 +/- 4.62 sec; P = 0.047). The hemoglobin level rose more in the rhGH than the placebo groups (change at 8 weeks, +0.84 +/- 0.34 vs. -0.42 +/- 0.29 g/dL; P = 0.012). Serum albumin level also showed a greater delayed increase in the rhGH group than in the placebo group (change at 8 weeks, +5.1 +/- 0.8 vs. 1.6 +/- 1.2 g/dL; P = 0.023). The
  • Journal article
    Bessis DN, Ledyaev YS, Vinter RB, 2001,

    Dualization of the Euler and Hamiltonian inclusions

    , NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS, Vol: 43, Pages: 861-882, ISSN: 0362-546X
  • Journal article
    Tang SC, Hui SYR, Chung H, 2001,

    Evaluation of the shielding effects on printed-circuit-board transformers using ferrite plates

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 4, Pages: 1919-1925, ISSN: 0275-9306

    This paper presents an effective shielding technique and a simple structure for printed-circuit-board (PCB) transformers. Performance of PCB transformers using the proposed shielding technique is evaluated using thin ferrite plates and copper sheets. Without affecting the transformer energy efficiency, the shielding method under investigation can achieve 28dB shielding effectiveness (SE), which is much higher than the SE (about 4dB) obtained by shielding the transformer windings with only two ferrite plates. The proposed PCB transformer structure is very simple and has high energy efficiency (>90%) for Megahertz operation.

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