K.M. Tsang

The Hong Kong Polytechnic University, Hong Kong, Hong Kong

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Publications (49)52.15 Total impact

  • K. M. Tsang, W. L. Chan, Y. K. Wong, L. Sun
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    ABSTRACT: Lithium-ion batteries are very popular nowadays. In order to design and evaluate the performance of systems involving batteries, good models are required for systems simulation. In this paper, popular lithium-ion battery models are investigated and presented. Selection of appropriate models for a particular simulation will also be presented.
    01/2010;
  • K. M. Tsang, L. Sun, W. L. Chan
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    ABSTRACT: A universal battery model for the charging process has been identified for Lithium ion battery working at constant temperature. Mathematical models are fitted to different collected charging profiles using the least squares algorithm. With the removal of the component which is related to the DC resistance of the battery, a universal model can be fitted to predict profiles of different charging rates after time scaling. Experimental results are included to demonstrate the goodness of fit of the model at different charging rates and for batteries of different capacities. Comparison with standard electrical-circuit model is also presented. With the proposed model, it is possible to derive more effective way to monitor the status of Lithium ion batteries, and to develop a universal quick charger for different capacities of batteries to result with a more effective usage of Lithium ion batteries.
    Energy Conversion and Management - ENERG CONV MANAGE. 01/2010; 51(12):2857-2862.
  • X.L. Wei, K.M. Tsang, W.L. Chan
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    ABSTRACT: An internal model control with conditional integrator is proposed for the robust output regulation of single-switch quadratic buck converters. The output regulation problem of a quadratic buck converter is converted to the stabilisation of an augmented system consisting of the buck converter and the internal model. The design procedures include the design of an internal model with conditional integrator and a robust state feedback stabiliser with saturation behaviour. The closed-loop stability of the converter will be theoretically analysed. Finally, the effectiveness of the proposed control scheme for large load and supply variations are also tested. The design of the controller does not require the exact circuit parameters and the stability proof demonstrates the robustness against parameter uncertainties.
    IET Power Electronics 10/2009; · 1.52 Impact Factor
  • K.M. Tsang, W.L. Chan
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    ABSTRACT: A simple equivalent series resistance (ESR) measurement technique for capacitors at high current and high frequency is presented. A low-cost square waveform voltage source coupled with a reference resistor can be used to measure the ESR of an electrolytic capacitor. By connecting a capacitor in series with a reference resistor, the ratio of the voltage magnitude across the capacitor to the voltage magnitude of the supply voltage reveals the ESR of the capacitor if the frequency of the supply source is sufficiently high. The square waveform voltage source can easily be realised using a DC voltage source and simple switching devices. An addition of a small inductor in series with the reference resistor could eliminate the effect of the equivalent series inductance and improve the measurement accuracy. A mathematical analysis is presented to demonstrate that the use of the square waveform and the addition of the small inductor are valid. Experimental results are included to demonstrate the effectiveness of the proposed scheme.
    IET Power Electronics 10/2009; · 1.52 Impact Factor
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    ABSTRACT: Intermodulation and harmonics are important in frequency analysis of nonlinear systems. In neuron research, most investigations are taken in studying synchronization between the external stimuli and the output of neuron, but harmonics and intermodulation are often ignored. In this paper, harmonics and intermodulation of the subthreshold FitzHugh-Nagumo neuron are investigated and their magnitudes are used to predict frequency response of the neuron. Furthermore, through analyzing the magnitudes of harmonics, the intrinsic frequencies of the neuron could be identified.
    Chaos (Woodbury, N.Y.) 09/2009; 19(3):033144. · 1.80 Impact Factor
  • Xile Wei, K. M. Tsang, W. L. Chan
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    ABSTRACT: An internal model control with a conditional integrator is proposed for the robust output regulation of a DC/DC buck converter. Based on the input–output linearization from the state-space averaged model of DC/DC buck converter, the robust output regulation problem of the converter can be converted into a robust stabilization problem of an augmented system consisting of the given buck converter and the internal model by introducing a proper internal model. The procedures include the design of an internal model with conditional integrator and a sliding-mode robust controller. Also the closed-loop robust stability is theoretically analyzed. Finally, the effectiveness of the proposed converter is verified in comparing the proposed controller performance with open-loop control, single-loop proportional-plus-integral control, and double-loop proportional-plus-integral control under load disturbances and supply voltage variations.
    Electric Power Components and Systems 03/2009; 37(3):320-330. · 0.62 Impact Factor
  • K. M. Tsang, W. L. Chan
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    ABSTRACT: A simple low-cost battery charger based on a saturated controller is proposed for charging of lithium-ion (Li-ion) batteries. When the reference voltage of the closed-loop process is set to 4.2V, the charging process resembles a constant-current and constant-voltage (CC–CV) charging strategy. The charging process can easily be shortened by raising the limit on the saturated controller. Experimental results are included to demonstrate the effectiveness of the charger. It is anticipated that the charger can be a low-cost high-performance replacement of existing Li-ion battery chargers.
    Journal of Power Sources 01/2009; 191(2):633-635. · 4.68 Impact Factor
  • K. M. Tsang, W. L. Chan
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    ABSTRACT: One of the key components in the current mode control of power converters is the sensing of inductor current. Traditional low cost implementation is to add a sensing resistor in series with the inductor to sense the inductor current. This will reduce the overall efficiency of the power converter. An alternative is to apply a current transformer to the inductor to sense its current. This however will significantly increase the cost of power converters. One low cost implementation is to add a resistor–capacitor network in parallel with the inductor so that the inductor current can be derived from the capacitor voltage. The problem of this implementation is that the capacitor voltage is very sensitive to temperature variations. In this paper, a simple feedback loop is applied to the sensed capacitor voltage based on the steady state duty ratio of power converters such that the sensed inductor current will be independent of temperature variations. The sensing element with feedback compensation can be applied to inductors fitted to power converters such as buck converters and boost converters. Although experimental studies based on a buck converter were carried out to illustrate the correctness of the new sensing technique, the proposed technique is applicable to other converter topologies.
    Sensors and Actuators A-physical - SENSOR ACTUATOR A-PHYS. 01/2009; 149(1):81-86.
  • K. M. Tsang, W. L. Chan
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    ABSTRACT: Inductor current sensing is very important in the control and monitoring of switching power converters. Traditional low cost implementation using a sensing resistor in series with the inductor will reduce the overall efficiency of the power converter. Conventional Hall effect current sensor could also be used to detect the inductor current. However, it will significantly increase the production cost of power converters. One simple and low cost implementation is to add a resistor–capacitor (RC) network in parallel with the inductor so that the inductor current can be derived from the added circuitry. The problem with RC sensing network is that the sensed variable is very sensitive to temperature variations. In this paper, a novel inductor current sensor using low cost negative temperature coefficient (NTC) thermistors to compensate the variation in the parasitic resistance of the inductor due to temperature changes is proposed. The changes in the cutoff frequency and steady state gain are also compensated by the added NTC thermistor circuit. With the compensated network, the sensed inductor current derived from the modified RC network will be independent of temperature variations. The compensated network can be applied to inductors fitted to power converters. Although experimental studies based on a buck converter were carried out to illustrate the correctness of the improved sensing technique, the proposed technique is applicable to other converter topologies.
    Sensors and Actuators A-physical - SENSOR ACTUATOR A-PHYS. 01/2009; 154(1):16-22.
  • K.M. Tsang, W.L. Chan, X.L. Wei
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    ABSTRACT: An internal model control using a conditional integrator compensator is proposed for the robust output regulation of a DC/DC buck converter. Based on the input-output linearisation from the state-space averaged model of the DC/DC buck converter, the robust output regulation problem of this type of converter can be converted into a robust stabilisation problem of an augmented system consisting of the given buck converter and the internal model by introducing a proper internal model. Another advantage of the proposed method is to sense the capacitor current instead of the inductor current. The effectiveness of the proposed converter is verified by comparing the proposed controller performance with single-loop PI control and double-loop PI control under load disturbances and supply voltage variations.
    Electronics Letters 02/2008; · 1.04 Impact Factor
  • K. M. Tsang, W. L. Chan
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    ABSTRACT: A model-based cascade controller design is presented for the control of DC/DC Buck converters. Detailed discussions in the setting of bandwidth for the current loop and voltage loop have been given. Robustness analysis of the cascade controller against load changes and supply changes are also presented. Finally, a deadband relay is introduced in the voltage loop to improve the disturbance rejection and speed of response of the Buck converter. Circuit implementation of the proposed control scheme is presented, and experimental results are included to demonstrate the effectiveness of the proposed design scheme. Comparisons with conventional single-loop proportional-plus-integral control and cascade control are also made.
    Electric Power Components and Systems - ELECTR POWER COMPON SYST. 01/2008; 36(9):977-989.
  • K. M. Tsang, W. L. Chan
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    ABSTRACT: The paper presents the design of a sensing system for non-destructive inspection of the health condition of wooden poles for overhead power lines. Acoustic impulse responses are collected for the analysis of the condition of different wooden poles. The concept of cumulative energy spectrum for feature extraction is introduced. Fuzzy logic is also used to solve the problem of small samples. Experimental results and the accuracy of the method are also presented.
    Sensors and Actuators A-physical - SENSOR ACTUATOR A-PHYS. 01/2008; 143(2):251-255.
  • K.M. Tsang, W.L. Chan
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    ABSTRACT: A simple, fast detection scheme for voltage dip and voltage swell is presented. Applying a simple relay and lowpass filter to the supply voltage signal, an in-phase fixed magnitude reference signal with very low total harmonic distortion can be generated. Comparing the supply signal with the in-phased fixed magnitude reference sinusoid, any change of magnitude in the supply signal can be detected. The detection scheme can indicate voltage dip and voltage swell in less than a quarter of the cycle of oscillation. Experimental results are presented to demonstrate the effectiveness of the proposed detection scheme
    Electronics Letters 02/2007; · 1.04 Impact Factor
  • K.M. Tsang, W.L. Chan
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    ABSTRACT: A very-low-cost active power filter with power-factor-correction capability for solving power quality problem is proposed. Model-based cascade controller design is presented for the control of the shunt active filter. Harmonic reductions and power-factor correction will both be carried out by the proposed filter. Discussions on the design of the current and voltage control loops are given. Circuit implementation of the proposed control scheme is presented and experimental results are included to demonstrate the effectiveness of the proposed design scheme
    IEE Proceedings - Electric Power Applications 10/2006; · 0.55 Impact Factor
  • K. M. Tsang, W. L. Chan
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    ABSTRACT: A search algorithm for the identification of multiple inputs nonlinear systems using the orthogonal least squares estimator is derived. Because of the high dimensionality of general nonlinear systems the forward regression algorithm is used to detect the plausible size of the final fitted model and a variation of the forward regression algorithm is proposed. Instead of choosing the best candidate term at each iteration, top few candidate terms which have the largest error reduction ratios are investigated at each iteration. A search algorithm coupled with the model predicted output is derived which will sort through all plausible candidate terms to produce an optimal solution for the problem. Simulated and experimental examples are included to demonstrate the effectiveness of the proposed algorithm.
    Electrical Engineering 05/2006; 88(5):357-365. · 0.30 Impact Factor
  • Wu Jun-wei, K. M. Tsang
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    ABSTRACT: In this paper, the robust Hinfin filter for the linear system with norm-bounded uncertainty is investigated. The uncertainty on the system matrices is represented in linear fractional representation (LFR) form which can approximate an uncertain input-output relation by a set of quadratic constrains; the constrained optimization problem is converted into an unconstrained dynamic game type problem by the so-called S-procedure theorem; the LMIs are used to analysis and synthesis the filter
    01/2006;
  • K. M. Tsang, W. L. Chan
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    ABSTRACT: A simple design method for power factor correction (PFC) boost converter is presented in this article. Model based cascade controller design is presented for the control of PFC boost converters. Detail discussions in the setting of bandwidth for the current loop and voltage loop have been given. Finally, a deadband relay is introduced in the voltage loop to improve the disturbance rejection and speed of response of the PFC boost converter. Circuit implementation of the proposed control scheme is presented and experimental results are included to demonstrate the effectiveness of the proposed design scheme. The resultant power factor is over 0.99, the total harmonic distortion of supply current is less than 2.9% and the efficiency of the converter is 93% at full load.
    Electric Power Components and Systems - ELECTR POWER COMPON SYST. 01/2006; 34(12):1267-1282.
  • K. M. Tsang, W. L. Chan, L. L. Lai
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    ABSTRACT: A rapid on-line frequency estimation algorithm with the help of non-linearity is presented. A full-wave rectification of the raw signal is carried out such that the fundamental frequency is doubled. The rectified signal is filtered and the signal frequency is extracted based on the filtered fundamental component and second order harmonics. Simulation example and real measurement are included to demonstrate the effectiveness of the algorithm.
    Electric Power Components and Systems 10/2005; 33(10):1137-1143. · 0.62 Impact Factor
  • K. M. Tsang, W. L. Chan
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    ABSTRACT: Conventional active power factor correction (PFC) converters are using classical PI controllers to carry out power factor correction. As the voltage input to the converter is fluctuating, a PI controller with nonlinear gain is proposed for the control of the supply current. To further reduce the total harmonic distortion of the supply current, a new reference current generation has been introduced. One of the novelties of the proposed approach is the possibility of generating reactive power for the converter to compensate loads outside the converter. Experimental studies are included to demonstrate the effectiveness of the proposed nonlinear PI controller.
    Electric Power Components and Systems 09/2005; 33(9):973-983. · 0.62 Impact Factor
  • K.M. Tsang, W.L. Chan
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    ABSTRACT: In order to deal with the increasing demand for good load and supply-voltage regulation of DC/DC convertors, a new cascade controller is proposed. The control of DC/DC buck convertor is first decomposed into a primary voltage-control loop and a secondary current-control loop. The cascade controller is then implemented based on the buck-converter settings with the dynamics of the secondary loop much faster than these of the primary loop. A robustness analysis of the cascade controller against load changes and supply changes is presented. Experimental results are included to demonstrate the effectiveness of the proposed control scheme over a conventional single-loop PI controller. The proposed controller can be implemented as a low-cost addon to a conventional single-loop controller. Detail design equations are presented.
    IEE Proceedings - Electric Power Applications 08/2005; · 0.55 Impact Factor

Publication Stats

69 Citations
52.15 Total Impact Points

Institutions

  • 2001–2013
    • The Hong Kong Polytechnic University
      • Department of Electrical Engineering
      Hong Kong, Hong Kong
  • 2005–2010
    • The University of Hong Kong
      • Department of Electrical and Electronic Engineering
      Hong Kong, Hong Kong
  • 2003–2010
    • Tianjin University
      • School of Electrical Engineering and Automation
      Tianjin, Tianjin Shi, China
    • Harbin Engineering University
      Charbin, Heilongjiang Sheng, China