Publications
496 results found
Yan S, Yang T, Lee CK, et al., 2016, Simultaneous Voltage and Current Compensation of the 3-Phase Electric Spring with Decomposed Voltage Control, 31st Annual IEEE Applied Power Electronics Specialists Conference and Exposition (APEC), Publisher: IEEE, Pages: 913-920, ISSN: 1048-2334
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- Citations: 1
Liu H, Lee CK, Hui RSY, et al., 2016, Capability Analysis and Design Considerations of Electric Springs, 7th IEEE International Symposium On Power Electronics for Distributed Generation Systems (PEDG), Publisher: IEEE, ISSN: 2329-5759
Zhang C, Lin D, Hui SYR, 2016, Efficiency Optimization Method of Inductive Coupling Wireless Power Transfer System with Multiple Transmitters and Single Receiver, 8th Annual IEEE Energy Conversion Congress and Exposition (ECCE), Publisher: IEEE, ISSN: 2329-3721
Ho GKY, Pong BMH, Hui RSY, 2016, LLC Resonant Converter Design for Bendable Power Converter, 31st Annual IEEE Applied Power Electronics Specialists Conference and Exposition (APEC), Publisher: IEEE, Pages: 2328-2333, ISSN: 1048-2334
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- Citations: 6
Huang Y, Xiong S, Tan S-C, et al., 2016, Compact Modular Switched-Capacitor DC/DC Converters with Exponential Voltage Gain, 31st Annual IEEE Applied Power Electronics Specialists Conference and Exposition (APEC), Publisher: IEEE, Pages: 1894-1899, ISSN: 1048-2334
Yang Y, Tan S-C, Hui S-YR, 2016, Voltage and Frequency Control of Electric Spring Based Smart Loads, 31st Annual IEEE Applied Power Electronics Specialists Conference and Exposition (APEC), Publisher: IEEE, Pages: 3481-3487, ISSN: 1048-2334
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- Citations: 17
Wang M-H, Tan S-C, Hui S-YR, 2016, Reduction of Storage Capacity in DC Microgrids Using PV-Embedded Series DC Electric Springs, 31st Annual IEEE Applied Power Electronics Specialists Conference and Exposition (APEC), Publisher: IEEE, Pages: 3302-3309, ISSN: 1048-2334
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- Citations: 6
Xiong S, Huang Y, Tan S-C, et al., 2016, Morphing Switched-Capacitor Step-Down DC-DC Converters with Variable Conversion Ratio, 31st Annual IEEE Applied Power Electronics Specialists Conference and Exposition (APEC), Publisher: IEEE, Pages: 1888-1893, ISSN: 1048-2334
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- Citations: 2
Yin J, Lin D, Parisini T, et al., 2015, Front-End Monitoring of the Mutual Inductance and Load Resistance in a Series-Series Compensated Wireless Power Transfer System, IEEE Transactions on Power Electronics, Vol: 31, Pages: 7339-7352, ISSN: 1941-0107
In this paper, a new method to estimate the mutual inductance and load resistance in a series-series compensated wireless power transfer system is presented. Reasonably accurate estimations can be obtained from measurements of the input voltage and current obtained at one operating frequency only. The proposal can be used to dynamically monitor both the coupling relationship between the transmitter and receiver coils and the load conditions without any direct measurement on the receiver side. It can also be used as a simple method to measure the mutual inductance of any pair of coupled coils. A novel impedance spectrum analysis method is further presented to show that series-series compensation has special characteristics in its input impedance spectrum. Experimental results with acceptable tolerance are included to show the effectiveness of the proposed method.
Chen H-T, Tan S-C, Hui SYR, 2015, Nonlinear Dimming and Correlated Color Temperature Control of Bicolor White LED Systems, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 30, Pages: 6934-6947, ISSN: 0885-8993
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- Citations: 36
Ho GKY, Zhang C, Pong BMH, et al., 2015, Modeling and Analysis of the Bendable Transformer, IEEE Transactions on Power Electronics, Vol: 31, Pages: 6450-6460, ISSN: 0885-8993
This paper presents a study of a bendable transformer for wearable electronics. Printed on a thin and bendable film, this transformer is bendable to wrap around body limbs such as the forearm. A model using a partial equivalent circuit theory has been developed to analyze the characteristic of an inductor and a bendable transformer. The mutual inductance and self-inductance for the bendable transformer over a range of bent curvatures have been calculated based on the model and compared favorably with measurements. Simulation and experimental results of applying the bendable inductor and transformer in dc-dc converters as a 5-V 500-mA power supply are included to confirm the usefulness of the transformer and the validity of the model.
Chen HT, Cheung YF, Choi HW, et al., 2015, Reduction of Thermal Resistance and Optical Power Loss Using Thin-Film Light-Emitting Diode (LED) Structure, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 62, Pages: 6925-6933, ISSN: 0278-0046
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- Citations: 10
Yan S, Tan SC, Hui SYR, 2015, Sliding mode control for improving the performance of PV inverter with MPPT - A comparison between SM and PI control
In this paper, we propose the use of sliding mode (SM) control to improve the maximum power point tracking (MPPT) performance of a two-stage single-phase inverter (comprising a first-stage DC/DC boost converter and a second-stage full-bridge inverter) in photovoltaic (PV) systems. To underscore the benefits of SM control, the MPPT performance of the PV system under the SM control is compared to that of an optimally-tuned proportional-integral (PI) control under the same PV system setup. To ease the comparison, a methodology of quantifying the measurements, which provides a clear graphical indication of the quality of the tracking, is proposed as a general platform to examine the performance. Experimental results show that the SM control can guarantee a better tracking accuracy over a larger operating range than the PI control when the weather conditions are changed dynamically throughout the course of a day. Additional comparisons based on the proposed methodology further supports that the SM control can improve the MPPT accuracy of the PV system, thus increasing the overall amount of energy harvested.
Yan S, Luo X, Tan SC, et al., 2015, Electric springs for improving transient stability of micro-grids in islanding operations, Pages: 5843-5850
Micro-grids fed with small synchronous generators and intermittent renewable power sources are generally considered as weak power grids unless very large energy storages are incorporated as the energy buffer. Auxiliary techniques are needed to improve their stability when transient interrupts occur. In this paper, the 3-ph Electric Spring (ES) is studied to improve the stability of the micro-grid in transient operations. The power compensation characteristics of the 3-ph ES are firstly analyzed. The linear relationships between decoupled d and q components of ES voltage and real and reactive power of smart load enable the ES to conduct frequency and voltage regulation simultaneously. The f-Vesd and V-Vesq droop control is further developed to coordinate the operation of multiple ESs distributed along a distribution line. The transient stability issues of the micro-grid under study are analyzed in detail. Simulation results show that the 3-ph ES implemented with f-Vesd and V-Vesq droop control can react swiftly to fast transient changes of micro-grids including intentional islanding, unintentional islanding, and sudden load changes.
Akhtar Z, Chaudhuri B, Hui S, 2015, Smart Loads for Voltage Control in Distribution Networks, IEEE Transactions on Smart Grid, Vol: 8, Pages: 937-946, ISSN: 1949-3061
This paper shows that the smart loads (SLs) couldbe effective in mitigating voltage problems caused by photovoltaic(PV) generation and electric vehicle (EV) chargingin low-voltage (LV) distribution networks. Limitations of thepreviously reported SL configuration with only series reactivecompensator (SLQ) (one converter) is highlighted in this paper.To overcome these limitations, an additional shunt converter isused in back-to-back (B2B) configuration to support the activepower exchanged by the series converter, which increases the flexibilityof the SL without requiring any energy storage. Simulationresults on a typical U.K. LV distribution network are presented tocompare the effectiveness of an SL with B2B converters (SLBCs)against an SLQ in tackling under- and over-voltage problemscaused by EV or PV. It is shown that SLBCs can regulate themain voltage more effectively than SLQs especially under overvoltagecondition. Although two converters are required for eachSLBC, it is shown that the apparent power capacity of eachconverter is required to be significantly less than that of anequivalent SLQ.
Ng WM, Hui SYR, 2015, Ultralow-Loss Passive T5 Fluorescent Lamp Ballasts for Subzero Temperature Operation, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 30, Pages: 5792-5799, ISSN: 0885-8993
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- Citations: 1
Zhong W, Hui SYR, 2015, Auxiliary Circuits for Power Flow Control in Multifrequency Wireless Power Transfer Systems With Multiple Receivers, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 30, Pages: 5902-5910, ISSN: 0885-8993
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- Citations: 69
Li S, Qi W, Tan SC, et al., 2015, Integration of an Active Filter and a Single-Phase AC/DC Converter with Reduced Capacitance Requirement and Component Count, IEEE Transactions on Power Electronics, Vol: 31, Pages: 4121-4137, ISSN: 0885-8993
Existing methods of incorporating an active filter into an AC/DC converter for eliminating electrolytic capacitors usually require extra power switches. This inevitably leads to an increased system cost and degraded energy efficiency. In this paper, a concept of active-filter integration for single-phase AC/DC converters is reported. The resultant converters can provide simultaneous functions of power factor correction, DC voltage regulation, and active power decoupling for mitigating the low-frequency DC voltage ripple, without an electrolytic capacitor and extra power switch. To complement the operation, two closed-loop voltage-ripple-based reference generation methods are developed for controlling the energy storage components to achieve active power decoupling. Both simulation and experiment have confirmed the eligibility of the proposed concept and control methods in a 210-W rectification system comprising an H-bridge converter with a half-bridge active filter. Interestingly, the end converters (Type I and Type II) can be readily available using a conventional H-bridge converter with minor hardware modification. A stable DC output with merely 1.1% ripple is realized with two 50-μF film capacitors. For the same ripple performance, a 900-μF capacitor is required in conventional converters without an active filter. Moreover, it is found out that the active-filter integration concept might even improve the efficiency performance of the end converters as compared with the original AC/DC converter without integration.
Yang Y, Mok K-T, Tan S-C, et al., 2015, Nonlinear Dynamic Power Tracking of Low-Power Wind Energy Conversion System, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 30, Pages: 5223-5236, ISSN: 0885-8993
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- Citations: 36
Li S, Zhu G-R, Tan S-C, et al., 2015, Direct AC/DC Rectifier With Mitigated Low-Frequency Ripple Through Inductor-Current Waveform Control, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 30, Pages: 4336-4348, ISSN: 0885-8993
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- Citations: 65
Zhong WX, Hui SYR, 2015, Maximum energy efficiency tracking for wireless power transfer systems, IEEE Transactions on Power Electronics, Vol: 30, Pages: 4025-4034, ISSN: 0885-8993
A method for automatic “maximum energy efficiency tracking” operation for wireless power transfer (WPT) systems is presented in this paper. Using the switched-mode converter in the receiver module to emulate the optimal load value, the proposed method follows the maximum energy efficiency operating points of a WPT system by searching for the minimum input power operating point for a given output power. Because the searching process is carried out on the transmitter side, the proposal does not require any wireless communication feedback from the receiver side. The control scheme has been successfully demonstrated in a two-coil system under both weak and strong magnetic coupling conditions. Experimental results are included to confirm its feasibility.
Cheung WS, Cheung YF, Chen HT, et al., 2015, InGaN light-emitting diode stripes with reduced luminous exitance, OPTICS EXPRESS, Vol: 23, Pages: 15021-15028, ISSN: 1094-4087
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- Citations: 5
Chen HT, Tan S-C, Hui SYR, 2015, Analysis and Modeling of High-Power Phosphor-Coated White Light-Emitting Diodes With a Large Surface Area, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 30, Pages: 3334-3344, ISSN: 0885-8993
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- Citations: 30
Chen B, Pin G, Ng WM, et al., 2015, A parallel prefiltering approach for the identification of a biased sinusoidal signal: theory and experiments, International Journal of Adaptive Control and Signal Processing, Vol: 29, Pages: 1591-1608, ISSN: 1099-1115
The problem of estimating the amplitude, frequency, and phase of an unknown sinusoidal signal from a noisy-biased measurement is addressed in this paper by a family of parallel prefiltering schemes. The proposed methodology consists in using a pair of linear filters of specified order to generate a suitable number of auxiliary signals that are used to estimate—in an adaptive way—the frequency, the amplitude, and the phase of the sinusoid. Increasing the order of the prefilters improves the noise immunity of the estimator, at the cost of an increase of the computational complexity. Among the whole family of estimators realizable by varying the order of the filters, the simple parallel prefilters of orders 2 + 2 and 3 + 3 are discussed in detail, being the most attractive from the implementability point of view. The behavior of the two algorithms with respect to bounded external disturbances is characterized by input-to-state stability arguments. Finally, the effectiveness of the proposed technique is shown both by comparative numerical simulations and by a real experiment addressing the estimation of the frequency of the electrical mains from a noisy voltage measurement.
Lee ATL, Tan SC, Hui SY, et al., 2015, Reset-sensing quasi-V<sup>2</sup> single-inductor multiple-output buck converter with reduced cross-regulation, Pages: 935-940
This paper proposes a reset-sensing quasi-V2 single-inductor multiple-output (SIMO) converter with minimal cross-regulation. The conventional quasi-V2 sensing scheme in SIMO converters suffers from serious cross-regulation which is primarily induced by the load differentiation with unbalanced loads. It is shown that the proposed reset-sensing quasi-V2 control scheme can significantly reduce cross-regulation by completely discharging the feed-forward sensing node to zero volts during the idle phase in Discontinuous Conduction Mode (DCM). The cross-regulation with the conventional quasi- V2 single-inductor dual-output (SIDO) converter for a load current step of 150 mA is experimentally verified to be more than 1.25 mV/mA. By employing the proposed quasi- V2 control method, the experimental results demonstrate that the cross-regulation for a load current step of 150 mA is significantly reduced to within 0.087 mV/mA. Hence, with the proposed scheme, a load transient in one output will have a minimal effect on the DC operating point of another output. This enables separate current control at each individually-driven output of a SIMO converter.
Yin J, Lin D, Lee CK, et al., 2015, Front-End Monitoring of Multiple Loads in Wireless Power Transfer Systems Without Wireless Communication Systems, IEEE Transactions on Power Electronics, Vol: 31, Pages: 2510-2517, ISSN: 0885-8993
This paper describes a method for monitoring multiple loads from the front end of a wireless power transfer system without using any wireless communication systems. A mathematical approach based on scanning the frequency around the resonant frequency has been developed for deriving the load conditions. The proposal requires only information of the input voltage and current, thereby eliminating the requirements of using wireless communication systems for feedback control. The proposal has been practically confirmed in hardware prototype with good results.
Mok KT, Tan SC, Hui SYR, 2015, Decoupled Power Angle and Voltage Control of Electric Springs, IEEE Transactions on Power Electronics, Vol: 31, Pages: 1216-1229, ISSN: 1941-0107
In this paper, a radial-chordal decomposition (RCD) technique is proposed to decouple the power angle and voltage control of a smart load based on the use of electric springs (ES). This RCD method is mathematically presented. A detailed comparison between the existing ES control schemes and the proposed RCD approach highlights its decoupling feature and merit on achieving multiple functionalities with a single ES. This RCD control method has been tested on a 2-kW small-scale power system. Simulation and experimental results confirmed that the power factor of the ES-integrated smart load can be improved by the chordal control while the mains voltage can be regulated by the radial control. It has also been demonstrated that the radial and chordal control can work simultaneously and independently.
Ron Hui SY, 2015, From the guest editor, IEEE Circuits and Systems Magazine, Vol: 15, ISSN: 1531-636X
Chen X, Hou Y, Tan S-C, et al., 2015, Mitigating voltage and frequency fluctuation in microgrids using electric springs, IEEE Transactions on Smart Grid, Vol: 6, Pages: 508-515, ISSN: 1949-3053
Voltage and frequency fluctuation associated with renewable integration have been well identified by power system operators and planners. At the microgrid level, a novel device for the implementation of dynamic load response, which is known as the electric springs (ES), has been developed for mitigating both active and reactive power imbalances. In this paper, a comprehensive control strategy is proposed for ES to participate in both voltage and frequency response control. It adopts the phase angle and amplitude control which respectively adjust the active power and the reactive power of the system. The proposed control strategy is validated using a model established with power system computer aided design/electro-magnetic transient in dc system. Results from the case studies show that with appropriate setting and operating strategy, ES can mitigate the voltage and frequency fluctuation caused by wind speed fluctuation, load fluctuation, and generator tripping wherever it is installed in the microgrid.
Kanna S, Dini DH, Xia Y, et al., 2015, Distributed widely linear kalman filtering for frequency estimation in power networks, IEEE Transactions on Signal and Information Processing over Networks, Vol: 1, Pages: 45-57, ISSN: 2373-776X
Motivated by the growing need for robust and accurate frequency estimators at the low and medium-voltage distribution levels and the emergence of ubiquitous sensors networks for the smart grid, we introduce a distributed Kalman filtering scheme for frequency estimation. This is achieved by using widely linear state space models, which are capable of estimating the frequency under both balanced and unbalanced operating conditions. The proposed distributed augmented extended Kalman filter (D-ACEKF) exploits multiple measurements without imposing any constraints on the operating conditions at different parts of the network, while also accounting for the correlated and noncircular natures of real-world nodal disturbances. Case studies over a range of power system conditions illustrate the theoretical and practical advantages of the proposed methodology.
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