Imperial College London

ProfessorShuHui

Faculty of EngineeringDepartment of Electrical and Electronic Engineering

Chair in Power Electronics
 
 
 
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Contact

 

+44 (0)20 7594 6118r.hui

 
 
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Location

 

1108aElectrical EngineeringSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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496 results found

Hui SYR, Lee ATL, Wu J, Tan SCet al., 2024, Analysis and Practical Evaluation of Dimmable Passive Light-Emitting Diode Drivers for Smart Lampposts, IEEE Transactions on Industrial Electronics, Vol: 71, Pages: 5704-5713, ISSN: 0278-0046

Passive light-emitting-diode (LED) drivers have recently been adopted by the lighting industry in street lighting applications due to their high robustness against extreme weather conditions, long lifetime, and high percentage of recyclable components. With the increasing trend of smart lamp posts, there are new requests for dimmable passive street lighting systems. This article presents a novel dimmable technology for passive LED drivers. By adding a switchable parallel capacitor across the input current-limiting inductor, a small freewheeling period between the inductor and capacitor can provide an artificial dead angle, which reduces the power for a passive half-bridge voltage doubler LED driver. The operating principle of this new dimming mechanism is explained, and a full analysis is included. The new dimmable mechanism has been practically confirmed in a 120-W passive LED system. The theoretical and practical results are in good agreement.

Journal article

Zeng J, Yang Y, Li K, Chen S, Hui SYRet al., 2024, An Ultrafast Estimation Method for Coupling Coefficient and Receiver Resonant Frequency in Universal Wireless Power Transfer Systems, IEEE Transactions on Power Electronics, Vol: 39, Pages: 4870-4883, ISSN: 0885-8993

This article proposes a fast and accurate front-end monitoring method to estimate the coupling coefficient and receiver resonant frequency of wireless power transfer (WPT) systems. The proposed method is developed for universal WPT systems with a series-compensated transmitter. The receiver parameters can be unknown and different from those on the transmitter side. This method is applicable to a range of receivers with first- or second-order compensation (i.e., series, parallel, and none-compensation). It can be extended to the systems with magnetic shielding, and has a strong immunity to the harmonics. Furthermore, a hardware-based identification approach is proposed for receiver compensation without any additional cost. The detection algorithms are analyzed in detail. The proposed scheme requires one additional phase detection sensor of the transmitter current. The zero-phase-angle frequencies of the WPT systems can be determined by fast frequency-sweeping processes with the receiver's active rectifier kept momentarily either short-circuited or open-circuited. Experimental results have been obtained to verify the proposed method, which can accurately estimate both coupling coefficients and receiver resonant frequencies within 2.5-8 ms.

Journal article

Yuan H, Lam HS, Liang G, Tan SC, Pou J, Ron Hui SYet al., 2024, Fault-Tolerant Control of Electric-Spring Enabled Solid-State Transformer Under Dual Active Bridge Failure, IEEE Journal of Emerging and Selected Topics in Power Electronics, Vol: 12, Pages: 118-128, ISSN: 2168-6777

The electric-spring (ES) technology is recently integrated into a solid-state transformer (SST) to support the power grid at the distribution voltage level and provide an 800-V dc grid for large-scale electric vehicle (EV) charging infrastructure. The ES-enabled SST (ES-SST) studied here consists of a diode-clamped converter (DCC) and several dual active bridges (DABs). The failure of one DAB could pose a big challenge to the balance of the dc-link capacitors and threatens the operation of the whole system. Existing voltage-balancing methods are not suitable for the faulty ES-SST due to the highly uneven distribution of the capacitor output power. In this article, a fault-tolerant control method is proposed to keep the capacitor voltages balanced under the DAB failure and maintain the operation of the system. The proposed control features a modulation algorithm to maximize the balancing capability of the DCC, the insertion of a zero-sequence voltage offset in the ac voltages, and the deliberate generation of reactive power. A numerical tool is also developed to predict the operability of the faulty system and design the controller. Simulation and experiments are conducted to verify the proposed control.

Journal article

Yang Y, Zeng J, Ron Hui SY, 2024, A Fast Primary-Side Current and Voltage Control for Direct Wireless Battery Chargers, IEEE Journal of Emerging and Selected Topics in Power Electronics, Vol: 12, Pages: 355-366, ISSN: 2168-6777

In traditional wireless power transfer (WPT) systems, constant current (CC) and constant voltage (CV)-based battery charging control strategies are applied to dc–dc converters on the receiver sides. In this study, the receiver-side control paradigm is shifted to the transmitter side and lumped as a primary-side current and voltage control that can: 1) rapidly determine the mutual inductances between the coupled coils regardless of misalignment (within tens of milliseconds); 2) eliminate dc–dc converters on the receiver sides; 3) implement constant frequency operations; and 4) automatically select current or voltage control mode without battery management chips and radio frequency (RF) communication. The combination of these four features offers a simple solution to reduce the complexities and sizes of receiver circuits for next-generation wireless battery chargers (WBCs). Only additional calibration circuits with limited components are required on the load ends. Both simulation and experimental results have validated the effectiveness of the proposed primary-side control for WBCs operating in both CC and CV modes. Practical results also showcase the automatic smooth transition from the CC mode to the CV mode.

Journal article

Zeng J, Chen S, Li K, Hui SYRet al., 2024, A Front-end Monitoring Method for Coupling Coefficient and Receiver Resonant Frequency in the SS-Compensated Wireless Power Transfer Systems with Unknown Receiver Parameters, IEEE Transactions on Power Electronics, ISSN: 0885-8993

In this paper, a front-end monitoring method is proposed to estimate the coupling coefficient and receiver resonant frequency in the series-series (SS) compensated wireless power transfer (WPT) systems. The proposal requires no prior knowledge of the receiver circuit parameters, such as the self-inductance of the coil, compensated capacitor, load resistance, and resonant frequency. Hence, it is suitable for the development of universal wireless charging systems and is immune against parameter tolerances and aging effects. It uses a sensing coil, which is decoupled from the transmitter coil but coupled with the receiver coil, to detect the phase information of the current on the receiver side. Only one zero-crossing sensor is required to detect the voltage information in the sensing coil. Two frequency sweeping processes are included to find the frequency points where the ac output voltage is in phase or out of phase with the ac input voltage. In the experiment, the estimation errors are less than 4.91% for the coupling coefficients and 1.33% for the receiver resonant frequencies. In addition, the estimation is extremely fast. The estimation time is within 5-9 ms

Journal article

Wang K, Zeng J, Yang Y, Hui SYRet al., 2024, A General Maximum Energy Efficiency Tracking Scheme for Domino Wireless Power Transfer Systems With Quasi-Load-Independent Outputs, IEEE Transactions on Power Electronics, Vol: 39, Pages: 1840-1852, ISSN: 0885-8993

This article presents a double-layer pulsewidth pulse-frequency based optimal control (PWPFC) in achieving maximum energy efficiency tracking (MEET) and quasi-load-independent (QLI) constant current (CC) and constant voltage (CV) outputs for domino wireless power transfer (WPT) systems with full considerations of equivalent series resistances. The proposed hierarchical control, which can be implemented using inexpensive digital controllers, is applied to the primary-side inverters based on the measured output current, output voltage, and phase angle of the receiver current via infrared communication. The upper layer (i.e., stage-I) of the PWPFC is a reference selection algorithm to provide references of operating frequencies and duty ratios for the tracking algorithm of the lower layer (i.e., stage-II). To ensure accurate tracking, a hill-climbing method is adopted to regulate the operating frequency of practical domino WPT systems with parasitic components and disturbance. Experimental results have verified the effectiveness of the proposed PWPFC in regulating domino WPT systems with MEET and QLI CC and CV outputs under various loads, compensation networks, and initial frequency conditions.

Journal article

Yan Z, Li K, Tan SC, Hui SYRet al., 2023, Design of a Single-Input Triple-Output Hybrid Converter With Decoupled Control for Reverse Electrodialysis Systems, IEEE Journal of Emerging and Selected Topics in Power Electronics, Vol: 11, Pages: 6124-6137, ISSN: 2168-6777

Reverse electrodialysis (RED) is a promising membrane-based technique on extracting salinity gradient power (SGP) from river water and seawater. Despite the prominent advantages of direct electricity conversion and abundant storage, RED stacks suffer from a low energy conversion efficiency, which renders optimized utilization of the attained power quite essential. Consequently, this article presents the design of a single-input triple-output hybrid converter with three independent control variables to address this issue. The hybrid converter integrates a buck converter and two switched-capacitor-based resonant converters (SCRCs) to deliver power from the RED stack to three output ports, including a water pump, a 48-V dc microgrid, and batteries. To avoid cross-coupling of power flow control among these ports, a decoupled control scheme is developed to achieve voltage regulation for the water pump, maximum-power-point-tracking (MPPT) of the RED stack, and battery charging current regulation independently. Moreover, the selection principles of resonant inductors and battery charging current are elaborated to derive the zero-voltage-switching (ZVS) operation regions of six switches under different operating conditions of RED stacks. Simulation and experimental results of both steady-state tests and dynamic tests validate the effectiveness of the proposed decoupled control scheme and ZVS regions.

Journal article

Yuan H, Lam HS, Beniwal N, Pou J, Hui S-YRet al., 2023, Modulation Methods for Balancing the Capacitor Voltages of N-Level Diode-Clamped Converters, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 70, Pages: 11887-11897, ISSN: 0278-0046

Journal article

Li K, Wu J, Yucel AC, Hui S-YRet al., 2023, New Printed-Circuit-Board Resonators With High Quality Factor and Transmission Efficiency for Mega-Hertz Wireless Power Transfer Applications, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 38, Pages: 13207-13218, ISSN: 0885-8993

Journal article

Yuan H, Lam HS, Beniwal N, Tan S-C, Pou J, Hui SYRet al., 2023, Cooperative Voltage-Balancing Control for Medium-Voltage ElectricSpring System Based on Diode-Clamped Converter and Dual Active Bridges, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 38, Pages: 11997-12009, ISSN: 0885-8993

Journal article

Zeng J, Wu J, Li K, Yang Y, Hui SYRet al., 2023, Dynamic Monitoring of Battery Variables and Mutual Inductance for Primary-Side Control of a Wireless Charging System, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, ISSN: 0278-0046

Journal article

Yuan H, Lam HS, Beniwal N, Tan S-C, Pou J, Hui S-YRet al., 2023, Direct-Switch Duty-Cycle Control of Grid-Connected n-Level Neutral-Point-Clamped Converter, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 70, Pages: 8624-8633, ISSN: 0278-0046

Journal article

Liang HWR, Yang Y, He L, Qu J, Lee CK, Hui SYRet al., 2023, A Multi-Hysteresis Control for Minimizing Battery Charging Time Within Industrial JEITA Guidelines, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 70, Pages: 8416-8425, ISSN: 0278-0046

Journal article

Zhou J, Li Z, Lee C-K, Chan KW, Hui SYRet al., 2023, A Weather-Independent and Renewable Power Supply With Wireless Power Transfer Feature for Powering Online Monitoring Systems in Smart Grid, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 70, Pages: 6414-6424, ISSN: 0278-0046

Journal article

Hui S-YR, Yang Y, Zhang C, 2023, Wireless Power Transfer: A Paradigm Shift for the Next Generation, IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS, Vol: 11, Pages: 2412-2427, ISSN: 2168-6777

Journal article

Yan Z, Huang Y, Tan S-C, Tang CY, Hui SYet al., 2023, A Self-Adaptive-Step-Size Incremental-Resistance-MPPT Technique for Reverse-Electrodialysis System, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 70, Pages: 3814-3824, ISSN: 0278-0046

Journal article

Wu J, Li S, Tan S-C, Hui SYRet al., 2023, Frequency Folding for LLC Resonant Converters in EV Charging Applications, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 38, Pages: 5041-5054, ISSN: 0885-8993

Journal article

Lam HS, Yuan H, Beniwal N, Liang G, Tan SC, Pou J, Hui SYRet al., 2023, Modeling and Practical Evaluation of AC-DC Solid-State Transformer With Electric Spring Functions, IEEE Transactions on Smart Grid, ISSN: 1949-3053

Power electronics (PE) devices have become ubiquitous in the modern power system. Their potential in participation in grid supporting has been gathering growing attention. PE-based electric spring (ES) technology has recently evolved from the low-voltage ac mains to the medium-voltage distribution network. When equipped with ES functions, solid-state transformers (SSTs) can be associated with energy storage and smart loads to absorb power fluctuations arising from renewable energy sources. Unlike previous studies in which PE systems are generally simplified as V, θ, P, Q, or represented by the simplest power converter topology, this paper implements and examines the grid-supporting functionality of a practical ES enabled-SST (ES-SST) system. The dynamic model of the ES-SST is presented and simulated, including both the circuit and control loops. Experimental results obtained from a scaled-down power system are also included to confirm the validity of the dynamic model in a microgrid environment. This dynamic model will facilitate smart-grid researchers to evaluate the use of a large group of distributed ES-SSTs in large power systems in future studies.

Journal article

Lam HS, Yuan H, Tan S-C, Mi CC, Pou J, Hui SYRet al., 2022, Bidirectional AC-DC Modular Multilevel Converter With Electric Spring Functions for Stabilizing Renewable AC Power Grid at the Distribution Voltage Level, IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS, Vol: 10, Pages: 7589-7600, ISSN: 2168-6777

Journal article

Zeng J, Chen S, Yang Y, Hui SYRet al., 2022, A Primary-Side Method for Ultrafast Determination of Mutual Coupling Coefficient in Milliseconds for Wireless Power Transfer Systems, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 15706-15716, ISSN: 0885-8993

Journal article

Li K, Tan S-C, Hui SYR, 2022, Interleaved Buck-Type Rectifier With Pseudo-DC-Link Capacitors for Automatic Current Balancing, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 69, Pages: 12676-12687, ISSN: 0278-0046

Journal article

Jiang Y, Yang Y, Tan S-C, Hui SYRet al., 2022, Power Loss Minimization of Parallel-Connected Distributed Energy Resources in DC Microgrids Using a Distributed Gradient Algorithm-Based Hierarchical Control, IEEE TRANSACTIONS ON SMART GRID, Vol: 13, Pages: 4538-4550, ISSN: 1949-3053

Journal article

Wu J, Li S, Tan S-C, Hui SYRet al., 2022, Fixed-Frequency Phase-Shift Modulated Capacitor-Clamped <i>LLC</i> Resonant Converter for EV Charging, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 13730-13742, ISSN: 0885-8993

Journal article

Beniwal N, Farivar GG, Lam HS, Ceballos S, Gorla NBY, Pou J, Hui SYR, Blaabjerg Fet al., 2022, Dual-Layer Pulsewidth Modulation Technique for Average Neutral Point Current Control in Neutral-Point-Clamped Converters, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 11762-11773, ISSN: 0885-8993

Journal article

Lam HS, Li P, Chen B, Ng WM, Parisini T, Hui SYRet al., 2022, Exponential modulation integral observer for online detection of the fundamental and harmonics in grid-connected power electronics equipment, IEEE Transactions on Control Systems Technology, Vol: 30, Pages: 1821-1833, ISSN: 1063-6536

Harmonic current estimation is required in active power filters for compensation purposes. The most efficient way of calculating the total harmonic current up to the infinite order is to subtract the fundamental component from the distorted current. Direct determination of the fundamental component of a distorted current of mains frequency was realized recently with a third-order modulation integral observer. This article shows that using an exponential modulation function (Exp-MF) for the integral observer will: 1) significantly enhance the robustness of the observer against noise and 2) automatically remove the low-frequency envelope arising from the D/A and A/C sampling processes compared to previous polynomial modulation function. These new and advantageous features are supported with detailed analysis and experimental verification. The robust observer can be implemented in grid-connected power electronics circuits that require the instantaneous information of the fundamental and/or harmonic currents. Practical comparative tests with the adaptive notch filter and recursive discrete Fourier transform (DFT) methods in an active power filter have confirmed the good performance under both the steady and dynamic states of the proposed Exp-MF integral observer.

Journal article

Jiang Y, Yang Y, Tan S-C, Hui SYRet al., 2022, A High-Order Differentiator Based Distributed Secondary Control for DC Microgrids Against False Data Injection Attacks, IEEE TRANSACTIONS ON SMART GRID, Vol: 13, Pages: 4035-4045, ISSN: 1949-3053

Journal article

Li H, Li S, Xiao W, Hui SYRet al., 2022, A Modulation Method for Capacitance Reduction in Active-Clamp Flyback-Based AC-DC Adapters, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 9455-9467, ISSN: 0885-8993

Journal article

Liang H-WR, Yang Y, Hui SYR, 2022, Improvement of Lithium-Ion Battery Charging From the State-of-the-Art Industrial JEITA Guidelines to a Hybrid Temperature-Regulated Current Control, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 6412-6423, ISSN: 0885-8993

Journal article

Lee ATL, Jin W, Tan S-C, Hui SYet al., 2022, Single-Inductor Multiple-Output (SIMO) Buck Hybrid Converter for Simultaneous Wireless and Wired Power Transfer, IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS, Vol: 10, Pages: 2163-2177, ISSN: 2168-6777

Journal article

Yan S, Hui SYR, 2022, A Simple Multi-Vector Predictive Direct Power Control Using Geometric Modulation, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 2899-2908, ISSN: 0885-8993

Journal article

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