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  • Journal article
    Tam PW, Hui SYR, Chung SH, 2006,

    An analysis and practical implementation of a dimmable compact fluorescent lamp ballast circuit without integrated circuit control

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

    Traditional compact fluorescent lamps (CFL) cannot be dimmed by triac dimmer. In this paper, the technical issues behind the incompatibility between the triac dimmer and the internal ballast of the compact fluorescent lamp are addressed. Based on the charge-pump concept and voltage dimming control, a dimmable CFL design that is compatible with triac dimmers is analyzed and developed. A 16W CFL prototype has been built and tested. Experiments have confirmed that a wide and stable dimming range from 2.2W to 16W can be achieved.
  • Journal article
    Cao XH, Hui SY, 2006,

    Use of auxiliary resonant tank to ensure soft-switching in high frequency electronic ballasts for metal halide lamps

    , IEEE Transactions on Power Electronics, Vol: 21, Pages: 1437-1443, ISSN: 0885-8993

    An auxiliary resonant tank-protected high-frequency electronic ballast and a pseudo-inductive soft-switching concept are proposed in this paper. Based on the steady state analysis of the series resonant converter, the operational characteristics of the ballast circuit for metal-halide (MH) lamps under different conditions are examined, and then potential hazards to the ballast circuit are addressed. To avoid those dangers, an auxiliary resonant tank is used for protecting the ballast circuit under all operations. With this auxiliary resonant tank operating in either inductive or pseudo-inductive modes, soft-switching can be ensured in the electronic ballasts. Feasibility of the proposal for the ballast circuit is verified by analytical and experimental results obtained from the 150-W prototype ballast for a MH lamp. © 2006 IEEE.
  • Journal article
    Yan W, Tam E, Hui SYR, 2006,

    A versatile semi-empirical PSpice fluorescent lamp model

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

    Based on a recently developed HID lamp model frame, a semi-empirical fluorescent lamp model optimized by genetic algorithms and easily implemented in PSpice 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. 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 can be achieved when the lamp power is reduced to 60% of rated power and when the lamp is 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.
  • Journal article
    Liu X, Hui SY, 2006,

    Optimal design of a hybrid winding structure for planar contactless battery charging platform

    , Conference Record - IAS Annual Meeting (IEEE Industry Applications Society), Vol: 5, Pages: 2568-2575, ISSN: 0197-2618

    Planar contactless battery charging platform is an emerging technology that has the potential of unifying the charging protocols of portable consumer electronic products. In this paper, a new hybrid structure which consists of a coil and a spiral winding is proposed for improving the uniform magnetic field distribution over the charging surface. An analysis into an optimal design of the number of turns and the dimension of the spiral winding is presented for a given concentrated coil. The uniform magnetic field distribution of the designed prototype is measured by an EMC scanner and by an energy-receiving coil. Based on circuit modeling and analysis, the inverter circuit topology and particularly the resonant compensation tank is designed for maximizing power transfer for multi-load applications. A design procedure is proposed and verified by the experiments. An efficiency of about 80% has been achieved for the coupling structure itself when four loads are charged on the platform simultaneously. © 2006 IEEE.
  • Journal article
    Yan W, Hui SYR, 2006,

    Dimming characteristics of large-scale high-intensity-discharge (HID) lamp lighting networks using a central energy-saving system

    , Conference Record - IAS Annual Meeting (IEEE Industry Applications Society), Vol: 3, Pages: 1090-1098, ISSN: 0197-2618

    This paper summarizes the test results on several largescale lighting systems based on a range of high-intensity-discharge (HID) lamps. The study focuses on the energy-saving, energy efficiency and dimming characteristics of magnetic-ballast-driven HID lamp systems that are suitable for public lighting networks. A central energy-saving unit that can change the input mains voltage of 220V to a variable voltage within 220V to 170V is used to control a large lighting network. This central dimming unit offers a new freedom for users to use lighting energy when and where it is needed and to an appropriate power level. Lamp characteristics under full and reduced voltage operation for 6 types of highintensity-discharge (HID) lamps have been measured. Six largescaled networks of ballast-lamp sets have been set up and dimmed with a central energy-saving unit with a rated power of 13.2kVA per phase. The full load current under test was set at about 40A per phase. The loss of the energy-saving unit on a per-lamp-set basis was measured at different voltage levels. It is found that the energy-saving unit can reduce overall system power at least 40% without causing lamp flickering. Through the controllable voltage range, there is no obvious change in color temperature. The lamp power and light output decrease almost linearly with input voltage within the range from 170V to 220V, and the power loss of the energy-saving unit is less than 2.4% of the full power in all tests. For these large-scaled lighting networks, it is envisaged an 25%-35% of energy-saving can be achieved in large public lighting applications. (c) 2006 IEEE.
  • Journal article
    Chan PKW, Chung HSH, Hui SYR, 2006,

    Boundary control of dynamic voltage restorers in voltage harmonic compensation

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

    Dynamic voltage restorer (DVR) is used to provide load voltage support and protect sensitive load during voltage sags situation. However, voltage sags do not appear frequently and hence the utilization of the DVR is low. In order to increase the utilization of the DVR, the DVR should operate to compensate any load voltage instability especially the load voltage harmonics and source voltage variations in steady-state operation. A boundary controller using a second-order switching surface is proposed for DVR application for both voltage sags and power quality control under steady-state condition. The switching surface is derived to estimate the state trajectory movement of the DVR after a hypothesized switching action. It results in a high state trajectory velocity along the switching surface. This phenomenon accelerates the trajectory moving towards the target operating point. The dynamic performance of the DVR is verified experimentally with distorted supply voltages, non-linear loads and distorted voltage sag situation. Experimental results confirm that the proposed boundary control scheme can achieve better harmonic compensation performance than some other control methods.
  • Journal article
    Rodriguez H, Astolfi A, Ortega R, 2006,

    On the construction of static stabilizers and static output trackers for dynamically linearizable systems, related results and applications

    , International Journal of Control, Vol: 79, Pages: 1523-1537, ISSN: 0020-7179
  • Conference paper
    Goulart PJ, Kerrigan EC, 2006,

    A Method for Robust Receding Horizon Output Feedback Control of Constrained Systems

    , 45th IEEE Conference on Decision and Control, 2006
  • Conference paper
    Goulart PJ, Kerrigan EC, 2006,

    A convex formulation for receding horizon control of constrained discrete-time systems with guaranteed l2 gain

    , 45th IEEE Conference on Decision and Control, 2006, Pages: 5447-5452
  • Conference paper
    Andrieu V, Praly L, Astolfi A, 2006,

    Nonlinear output feedback design via domination and generalized weighted homogeneity

    , Pages: 6391-6396
  • Conference paper
    Carnevale D, Karagiannis D, Astolfi A, 2006,

    Reduced-order observer design for systems with non-monotonic nonlinearities

    , Pages: 5269-5274
  • Journal article
    Allwight JC, Abdullah S, 2006,

    An active learning approach for radial basis function neural networks

    , Jurnal Teknologi, Penerbit Universiti Teknologi Malaysia, Pages: 77-96
  • Conference paper
    Back J, Astolfi A, 2006,

    Existence Conditions and a Constructive Design of Positive Linear Observers for Positive Linear Systems

    , Pages: 4734-4739
  • Conference paper
    Schiavo F, Lovera M, Astolfi A, 2006,

    Magnetic attitude control of spacecraft with flexible appendages

    , Pages: 1545-1550
  • Conference paper
    Tan Y, Nesic D, Mareels I, Astolfi Aet al., 2006,

    On global extremum seeking in the presence of local extrema

    , Pages: 5663-5668
  • Conference paper
    Tanelli M, Astolfi A, Savaresi S, 2006,

    Robust Nonlinear Proportional-Integral Control for Active Braking Control Systems

    , Pages: 1745-1750
  • Conference paper
    Brucoli M, Green TC, 2006,

    Fault response of inverter dominated microgrids

    , 2nd International Conference on Integration of Renewable and Distributed Energy Resources
  • Conference paper
    Talasila V, Astolfi A, Clemente-Gallardo J, 2006,

    Controlled Invariant Manifolds: a Normally-Hyperbolic Viewpoint

    , Pages: 5863-5868
  • Conference paper
    Clark, J M C, Vinter R B, 2006,

    A New Class of Moment Matching Filters for Nonlinear Tracking and Estimation Problems
  • Conference paper
    Laila D S, Lovera M, Astolfi A, 2006,

    A numerical algorithm as an observer for spacecraft attitude determination

    , Pages: 1568-1573
  • Conference paper
    Rakovic S V, Teel A R, Mayne D Q, Astolfi Aet al., 2006,

    Simple Robust Control Invariant Tubes for Some Classes of Nonlinear Discrete Time Systems

    , Pages: 6397-6402
  • Journal article
    Tam PW, Lee STS, Hui SYR, Chung HSHet al., 2006,

    Practical evaluation of dimming control methods for electronic ballasts

    , IEEE Transactions on Power Electronics, Vol: 21, Pages: 1769-1775, ISSN: 0885-8993

    The authors compare and evaluate 1) the traditional frequency-control dimming method and 2) a recently-patented voltage-control dimming method in electronic ballasts for fluorescent lamps. The power factor, energy efficiency, electronic loss, efficacy (lumen/W), and crest factor of 2 × 36 W electronic ballasts based on these two dimming methods are recorded and compared over a wide dimming range. It is found that the voltage dimming control approach is much better than the frequency control method in most of the compared aspects as the lamp is dimmed. In particular, voltage dimming approach has much higher energy efficiency and lumen per watt than the frequency control one. Unlike the frequency dimming method, voltage dimming control has a distinctive feature in that its electronic loss decreases with decreasing lamp power. © 2006 IEEE.
  • Journal article
    Black M, Strbac G, 2006,

    Value of storage in providing balancing services for electrcity generation systems with high wind penetration

    , Journal of Power Sources, Vol: 162, Pages: 949-953
  • Book chapter
    Maciejowski J M, Goulart P J, Kerrigan E C, 2006,

    Constrained control using model predictive control

    , Advanced strategies in control systems with input and output constraints, Editors: Editor, Editor, Editor, ISBN: 9783540370093
  • Conference paper
    Feng C, Liang J, Agelidis AG, Green TCet al., 2006,

    A Multi-Modular System Based On Parallel-Connected Multilevel Flying Capacitor Converters Controlled with Fundamental Frequency SPWM

    , IEEE Induistrial Electronics Conf. IECON 2006, Pages: 2360-2365
  • Conference paper
    Mitcheson P D, Reilly E K, Wright P K, Yeatman E Het al., 2006,

    Transduction Mechanisms and Power Density for MEMS Inertial Energy Scavengers

    , Pages: 275-278
  • Conference paper
    D'Hulst R, Mitcheson PD, Driesen J, 2006,

    CMOS Buck-Boost Power processing circuitry for powerMEMS generators

    , Pages: 215-218
  • Journal article
    Chan PKW, Leung KKS, Chung HSH, Hui SYRet al., 2006,

    Boundary controller for dynamic voltage restorers to achieve fast dynamic response

    , Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, Vol: 2006, Pages: 1379-1384

    The performance of using second-order switching surface in boundary control of dynamic voltage restorers (DVR) for improving the voltage stability of power system is examined. The switching surface is derived to estimate the state trajectory movement of the DVR after a hypothesized switching action. It results in a high state trajectory velocity along the switching surface. This phenomenon accelerates the trajectory moving towards the target operating point. The proposed boundary control method has been studied with computer simulations, as well as a low-power prototype. The dynamic responses of the DVR with different voltage sags and different loads, including a resistive load, inductive load and nonlinear load have been examined. It has been shown that the proposed boundary control scheme can achieve a faster transient and damping responses than the other control methods. © 2006 IEEE.
  • Journal article
    Zhong Q-C, Liang J, Weiss G, Feng C, Green TCet al., 2006,

    H<SUP>∞</SUP> control of the neutral point in four-wire three-phase DC-AC converters

    , IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 53, Pages: 1594-1602, ISSN: 0278-0046
  • Conference paper
    Caines P E, Clarke F H, Liu X, Vinter R Bet al., 2006,

    A Maximum Principle for Hybrid Optimal Control Problems with Pathwise State Constraints

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