Publications

Search or filter publications

Filter by type:

Filter by publication type

Filter by year:

to

Results

  • Showing results for:
  • Reset all filters

Search results

  • Journal article
    Yip SC, Qiu DY, Chung HSH, Hui SYRet al., 2003,

    A Novel Voltage Sensorless Control Technique for a Bidirectional AC/DC Converter

    , IEEE Transactions on Power Electronics, Vol: 18, Pages: 1346-1355, ISSN: 0885-8993

    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-side 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) inherent electrical isolation and reducing noise coupling between the power circuit and the controller; 2) wide operating range. Design criteria for the differentiator and the envelope detector circuit has been described. The applicability of the proposed method is verified with the experimental results of a laboratory prototype.
  • Journal article
    Karagiannis D, Mendes E, Astolfi A, Ortega Ret al., 2003,

    An experimental comparison of several PWM controllers for a single-phase AC-DC converter

    , IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, Vol: 11, Pages: 940-947, ISSN: 1063-6536
  • Journal article
    Chryssochoos I, Vinter RB, 2003,

    Optimal control problems on manifolds: a dynamic programming approach

    , JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS, Vol: 287, Pages: 118-140, ISSN: 0022-247X
  • Journal article
    Arutyunov AV, Vinter RB, 2003,

    A finite-dimensional approximation method in optimal control theory

    , DIFFERENTIAL EQUATIONS, Vol: 39, Pages: 1519-1528, ISSN: 0012-2661
  • Journal article
    Green TC, Hernandez-Aramburo CA, Smith AC, 2003,

    Losses in grid and inverter supplied induction machine drives

    , IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS, Vol: 150, Pages: 712-724, ISSN: 1350-2352
  • Journal article
    Angeli D, Sontag ED, Wang Y, 2003,

    Input to state stability with respect to inputs and their derivatives

    , International Journal of Robust and Nonlinear Control, Vol: 13, Pages: 1035-1056
  • Journal article
    Vinter RB, Zheng H, 2003,

    Some finance problems solved with nonsmooth optimization techniques

    , JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS, Vol: 119, Pages: 1-18, ISSN: 0022-3239
  • Journal article
    Antonelli R, Astolfi A, 2003,

    Continuous stirred tank reactors: easy to stabilise?

    , AUTOMATICA, Vol: 39, Pages: 1817-1827, ISSN: 0005-1098
  • Journal article
    Prieur C, Astolfi A, 2003,

    Robust stabilization of chained systems via hybrid control

    , IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 48, Pages: 1768-1772, ISSN: 0018-9286
  • Journal article
    Angeli D, Sontag ED, 2003,

    Monotone Control Systems

    , IEEE Transactions on Automatic Control, Vol: 48, Pages: 1684-1698
  • Journal article
    Galbraith GN, Vinter RB, 2003,

    Optimal control of hybrid systems with an infinite set of discrete states

    , J DYN CONTROL SYST, Vol: 9, Pages: 563-584, ISSN: 1079-2724

    Hybrid control systems are described by a family of continuous subsystems and a set of logic rules for switching between them. This paper concerns a broad class of optimization problems for hybrid systems, in which the continuous subsystems are modelled as differential inclusions. The formulation allows endpoint constraints and a general objective function that includes "transaction costs" associated with abrupt changes of discrete and continuous states, and terms associated with continuous control action as well as the terminal value of the continuous state. In consequence of the endpoint constraints, the value function may be discontinuous. It is shown that the collection of value functions (associated with all discrete states) is the unique lower semicontinuous solution of a system of generalized Bensoussan-Lions type quasi-variational inequalities, suitably interpreted for nondifferentiable, extended valued functions. It is also shown how optimal strategies and value functions are related. The proof techniques are system theoretic, i.e., based on the construction of state trajectories with suitable properties. A distinctive feature of the analysis is that it permits an infinite set of discrete states.
  • Journal article
    Green TC, Marks JH, 2003,

    Ratings of active power filters

    , IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS, Vol: 150, Pages: 607-614, ISSN: 1350-2352
  • Journal article
    Lu HY, Zhu JG, Hui SYR, 2003,

    Experimental determination of stray capacitances in high frequency transformers

    , IEEE Transactions on Power Electronics, Vol: 18, Pages: 1105-1112, ISSN: 0885-8993

    This paper presents practical techniques for determining stray capacitances in a two-winding high frequency transformer for circuit simulation and computer-aided design purposes. These techniques fall into two categories: 1) the two-port network approach; 2) the step-response approach. The first approach can be employed for high frequency transformer circuit models with the effect of stray capacitances modeled as a π-shape network of three lumped stray capacitances. The second approach is useful for the transformer circuit model with the overall effects of stray capacitances modeled as lumped stray-capacitance connected cross the primary side. These techniques have been verified in the modeling and numerical simulation of a 500 W 25 kHz two winding E-core transformer. The merits and limitations of these techniques are also discussed.
  • Conference paper
    Mitcheson PD, Stark BH, Miao P, Yeatman EM, Holmes AS, Green TCet al., 2003,

    Analysis and optimisation of MEMS electrostatic on-chip power supply for self-powering of slow-moving sensors

    , Guimaraes, Eurosensors 03, 17th European conference on sensors and actuators, University of Minho Guimaraes, Portugal, 21 - 24 September 2003, Publisher: University of Minho, Pages: 48-51
  • Journal article
    Lee CK, Leung JSK, Hui SYR, Chung HSHet al., 2003,

    Circuit-level comparison of STATCOM technologies

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 4, Pages: 1777-1784, ISSN: 0275-9306

    This paper performs a circuit-level evaluation of four modern STATCOM systems, namely True-48-Pulse and Quasi-48-Pulse STATCOMs, Cascade Multilevel and Binary Multilevel Inverters. The comparison is based on a number of factors including circuit topology, harmonic distortion, system losses, GTO quantities, their specific applications and other considerations. The theoretical results are verified by simulation with the use of MATLAB-Simulink Power System Blockset.
  • Journal article
    Qiu DY, Hui SY, Chung SH, 2003,

    Parameter monitoring of high-frequency electronically operated discharge lamp systems

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 3, Pages: 1341-1346, ISSN: 0275-9306

    Arc discharge loads such as discharge lamps require high ignition voltage (several kilo-volt to 20 kilo-Volts), but have low on-state voltage (typically 100V). For discharge arc monitoring purposes, it is difficult or uneconomical to Implement voltage sensor to cover such a wide range of voltage. In this paper, a non-intrusive and electrically isolated method, based on the single-sensor principle, is used to derive the system parameters and variables for system monitoring and control purposes. Only one coupled winding is used to derive the converter inductor voltage, from which the lamp power, lamp arc resistance and inverter dc link voltage can be accurately derived. The proposal is verified with good agreement between derived values and measurements in an electronic ballast - fluorescent lamp system. The proposal can be useful in applications in which sensing the voltage across the load is either difficult or costly.
  • Journal article
    Lee SST, Chung HSH, Hui SYR, 2003,

    A comparative study of random switching schemes for eliminating visible striations in fluorescent lamps

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 3, Pages: 1006-1011, ISSN: 0275-9306

    This paper presents a comparative study of using random switching modulation schemes for the resonant inverter in electronic ballasts to eliminate visible striation (appearance of black and white bands along the tube) in fluorescent lamps. As striations can be eliminated by superimposing a small amount of dc current or low frequency ac current to the electrodes to produce composite current waveform through the lamp, the underlying principle of this work is based on the fact that random switching introduces low-frequency harmonics at the inverter output. Although this inherent low-frequency generation characteristics is generally undesirable for switching converters requiring high quality output, it provides a favorable means to eliminate striations in this particular application. Modulation schemes under investigation include random pulse position modulation, randomized pulse width modulation (RPWM) and randomized carrier frequency modulation. Issues addressed include the effectiveness of each scheme in eliminating the striations and the randomness level on lamp flickers. Among the schemes, RPWM is found to be the best choice as it introduces largest amount of low-frequency lamp current. The validity of the analyses Is confirmed experimentally by using a T8 36W prototype.
  • Journal article
    Lee SST, Chan S, Chung HSH, Hui SYRet al., 2003,

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

    , PESC Record - IEEE Annual Power Electronics Specialists Conference, Vol: 3, Pages: 988-993, ISSN: 0275-9306

    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, resulting in a wider dimming range and improved controllability. The method gives a simple solution of improving the dimming characteristics without changing the circuit structure. Theoretical predictions are verified with the experimental results of a 36W T8 prototype.
  • Journal article
    Chaudhuri B, Pal BC, Zolotas AC, Jaimoukha IM, Green TCet al., 2003,

    Mixed-sensitivity approach to H-infinity control of power system oscillations employing multiple FACTS devices

    , IEEE TRANSACTIONS ON POWER SYSTEMS, Vol: 18, Pages: 1149-1156, ISSN: 0885-8950
  • Journal article
    Leung KKS, Chung HSH, Hui SYR, 2003,

    Use of state trajectory prediction in hysteresis control for achieving fast transient response of the buck converter

    , Proceedings - IEEE International Symposium on Circuits and Systems, Vol: 3, ISSN: 0271-4310

    A dynamic hysteresis control of the buck converter for achieving high slew-rate response to disturbances is proposed. The hysteresis band is derived from the output capacitor current that predicts the output voltage magnitude after a hypothesized switching action. Four switching criteria are formulated to dictate the state of the main switch. The output voltage can revert to the steady state in two switching actions after a large-signal disturbance. The technique is verified with the experimental results of a 50W buck converter.
  • Journal article
    Valtolina E, Astolfi A, 2003,

    Local robust regulation of chained systems

    , SYSTEMS & CONTROL LETTERS, Vol: 49, Pages: 231-238, ISSN: 0167-6911
  • Journal article
    Yan W, Hui SYR, Chung H, 2003,

    Nonlinear high-intensity discharge lamp model including a dynamic electrode voltage drop

    , IEE Proceedings: Science, Measurement and Technology, Vol: 150, Pages: 161-167, ISSN: 1350-2344

    Based on the physical laws of plasma arc discharge, an accurate nonlinear dynamic high-intensity discharge (HID) lamp model that includes the dynamic electrode voltage drop equation has been developed. The physical model includes the hysteresis effect in the high, frequency V-I characteristic caused by the physical process of electrode regions and can predict lamp terminal characteristics accurately over a wide frequency range. The key advantage of the model is that all parameters can be obtained from typical electrical terminal measurements of the HID lamps without using information that is either unavailable from lamp manufacturers or difficult to measure practically. Simulated and measured results have been used to verify the model. The proposed model provides a powerful tool for simulating the electrical behaviour of the HID lamps and thus can be used as a design tool for electronic ballasts for HID lamps.
  • Journal article
    Lee CK, Leung JSK, Hui SYR, Chung HSHet al., 2003,

    Circuit-level comparison of STATCOM technologies

    , IEEE Transactions on Power Electronics, Vol: 18, Pages: 1084-1092, ISSN: 0885-8993

    This paper performs a comprehensive circuit-level evaluation of four modern STATCOM systems, namely true-48-pulse and quasi-48-pulse STATCOMs, cascade multilevel and binary multilevel inverters. The comparison is based on a number of factors including circuit topology, harmonic distortion, system losses, GTO quantities, their specific applications, and other considerations. The theoretical results are verified by simulation with the use of MATLAB-Simulink Power System Blockset.
  • Journal article
    Qiu DY, Yip SC, Chung HSH, Hui SYRet al., 2003,

    On the use of current sensors for the control of power converters

    , IEEE Transactions on Power Electronics, Vol: 18, Pages: 1047-1055, ISSN: 0885-8993

    This paper describes the use of current sensors for the control of power converters. No voltage sensor is required in the whole system. The sensed current and the rate of change of the inductor current in different circuit topologies are used to determine the input and output voltages of the converters, and for current programming and maximum current protection. Apart from reducing the number of sensors, the proposed method provides inherent electrical isolation between the power conversion stage and the controller and lessens noise-coupling problems. The proposed technique is illustrated with a current-programmed dc/dc boost regulator with feedforward and feedback control. The regulator's steady state and transient responses under input source and output load disturbances are presented.
  • Journal article
    Antonelli R, Harmand J, Steyer JP, Astolfi Aet al., 2003,

    Set-point regulation of an anaerobic digestion process with bounded output feedback

    , IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, Vol: 11, Pages: 495-504, ISSN: 1063-6536
  • Conference paper
    Chaudhuri B, Green TC, Jaimoukha IM, Pal BC, Zolotas ACet al., 2003,

    Mixed-sensitivity approach to h(infinity) control of power system oscillations employing multiple facts devices

    , General meeting of IEEE Power Engineering Society, Toronto, Canada, Publisher: IEEE, Pages: 2348-2348
  • Journal article
    Jabr RA, Pal BC, 2003,

    Iteratively re-weighted least absolute value method for state estimation

    , IEE P-GENER TRANSM D, Vol: 150, Pages: 385-391, ISSN: 1350-2360

    A modified version of the weighted least absolute value (WLAV) method for the solution of the power system-state-estimation problem is presented. The WLAV method can be seen as minimising a linear objective function subject to a set of nonlinear constraints. The modification is aimed at producing a WLAV estimator that remains insensitive to bad data, even if they are associated with leverage-point measurements. This is achieved by bending the linear objective function, so that the residuals of bad measurements are allowed to grow without incurring much additional cost in the objective function. Consequently, the optimisation procedure would find an optimal solution where the residuals of all bad measurements are nonzero. The optimisation is carried out via sequential linear programming. It is shown that each linear program corresponds to a linearised WLAV problem with weights adjusted automatically during the iterations. To ensure fast execution time, the linear program is solved using a homogeneous interior-point method. Computational results show that the proposed method can identify bad data in leverage points.
  • Conference paper
    Chaudhuri B, Pal BC, Zolotas AC, Jaimoukha IM, Green TCet al., 2003,

    Mixed-Sensitivity Approach to H-infinity Control of Power System Oscillations Employing Multiple FACTS Devices
  • Journal article
    Ortega R, Hsu L, Astolfi A, 2003,

    Immersion and invariance adaptive control of linear multivariable systems

    , SYSTEMS & CONTROL LETTERS, Vol: 49, Pages: 37-47, ISSN: 0167-6911
  • Journal article
    Chung HSH, Tse KK, Ron Hui SY, Mok CM, Ho MTet al., 2003,

    A novel maximum power point tracking technique for solar panels using a SEPIC or Cuk converter

    , IEEE Transactions on Power Electronics, Vol: 18, Pages: 717-724, ISSN: 0885-8993

    A novel technique for efficiently extracting the maximum output power from a solar panel under varying meteorological conditions is presented. The methodology is based on connecting a pulse-width-modulated (PWM) dc/dc SEPIC or Cuk converter between a solar panel and a load or battery bus. The converter operates in discontinuous capacitor voltage mode whilst its input current is continuous. By modulating a small-signal sinusoidal perturbation into the duty cycle of the main switch and comparing the maximum variation in the input voltage and the voltage stress of the main switch, the maximum power point (MPP) of the panel can be located. The nominal duty cycle of the main switch in the converter is adjusted to a value, so that the input resistance of the converter is equal to the equivalent output resistance of the solar panel at the MPP. This approach ensures maximum power transfer under all conditions without using microprocessors for calculation. Detailed mathematical derivations of the MPP tracking technique are included. The tracking capability of the proposed technique has been verified experimentally with a 10-W solar panel at different insolation (incident solar radiation) levels and under large-signal insolation level changes.

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://wwwtest.imperial.ac.uk:80/respub/WEB-INF/jsp/search-t4-html.jsp Request URI: /respub/WEB-INF/jsp/search-t4-html.jsp Query String: id=955&limit=30&page=62&respub-action=search.html Current Millis: 1759608433499 Current Time: Sat Oct 04 21:07:13 BST 2025