Henry Chung

Henry Chung

City University of Hong Kong

H-index: 79

Asia-Hong Kong

About Henry Chung

Henry Chung, With an exceptional h-index of 79 and a recent h-index of 41 (since 2020), a distinguished researcher at City University of Hong Kong, specializes in the field of Power Electronics.

His recent articles reflect a diverse array of research interests and contributions to the field:

Open-Circuit Fault Diagnosis and Fault-Tolerant Control for a Coupled-Inductor-Based Aalborg Inverter

Achieving Fast Dynamic Response and Output Filter Condition Monitoring in Hybrid PWM Inverters Using a Low-Computational State Trajectory Prediction Algorithm Incorporating …

Enhancing Stability of DC Cascaded Systems with CPLs using MPC Combined with NI And Accounting for Parameter Uncertainties

Resonant and soft-switching converters

A Galvanic-Isolated Automatic Equalization Charging System for Series-Connected Cells or Battery Strings

Active Damping of LLCL‐Filter Resonance Based on LC‐Trap Voltage or Current Feedback

Modeling and Suppressing Conducted Electromagnetic Interference Noise for LCL/LLCL‐Filtered Single‐Phase Transformerless Grid‐Connected Inverter

An ANN-based output-error-driven incremental model predictive control for buck converter against parameter variations

Henry Chung Information

University

City University of Hong Kong

Position

Chair Professor of Electrical Engineering

Citations(all)

23067

Citations(since 2020)

8386

Cited By

18314

hIndex(all)

79

hIndex(since 2020)

41

i10Index(all)

286

i10Index(since 2020)

160

Email

University Profile Page

City University of Hong Kong

Henry Chung Skills & Research Interests

Power Electronics

Top articles of Henry Chung

Open-Circuit Fault Diagnosis and Fault-Tolerant Control for a Coupled-Inductor-Based Aalborg Inverter

Authors

Ui-Min Choi,June-Seok Lee,Frede Blaabjerg,Kyo-Beum Lee

Journal

IEEE Transactions on Power Electronics

Published Date

2015/12/17

This paper presents an open-circuit fault detection method for a grid-connected neutral-point clamped (NPC) inverter system. Further, a fault-tolerant control method under an open-circuit fault in clamping diodes is proposed. Under the grid-connected condition, it is impossible to identify the location of a faulty switch by the conventional methods which usually use the distortion of outputs because the distortion of the outputs is the same in some fault cases. The proposed fault detection method identifies the location of the faulty switch and the faulty clamping diode of the NPC inverter without any additional hardware or complex calculations. In the case of the clamping diode faults, the NPC inverter can transfer full rated power with sinusoidal currents by the proposed fault-tolerant control. The feasibility of the proposed fault detection and the fault-tolerant control methods for the grid-connected NPC inverter are verified …

Achieving Fast Dynamic Response and Output Filter Condition Monitoring in Hybrid PWM Inverters Using a Low-Computational State Trajectory Prediction Algorithm Incorporating …

Authors

Jacky Chun Tak Lai,Shun Cheung Ryan Yeung,Henry Shu-Hung Chung

Journal

IEEE Transactions on Power Electronics

Published Date

2024/3/19

This paper presents a novel state trajectory prediction algorithm with reduced-order switching surfaces, designed for H-bridge inverters using hybrid pulse-width modulation ( h -PWM). h -PWM hybridizes the merits of unipolar 2-level switching scheme (U2SS) and bipolar 3-level switching scheme (B3SS), operating mainly in U2SS while temporarily transitioning to B3SS near the zero-crossing region to resolve the impact of pulse droppings. The algorithm predicts the state trajectory for the entire switching cycle, facilitating fast control and fast dynamic response. By sampling the state variable once at the beginning of each switching cycle, the duty ratios of all switching devices are established for the entire cycle. Since the effective operating frequency under h -PWM is twice the switching frequency, the values of the output filter components are minimized, and thus the power density can be increased. Furthermore, the …

Enhancing Stability of DC Cascaded Systems with CPLs using MPC Combined with NI And Accounting for Parameter Uncertainties

Authors

Hongjian Lin,Henry Shu-Hung Chung,Ruihua Shen,Yangxiao Xiang

Journal

IEEE Transactions on Power Electronics

Published Date

2024/1/29

Compared with the traditional passive- and activedamping techniques for mitigating the impedance mismatch between the input impedance of constant power loads (CPLs) and the output impedance of the DC link within DC microgrids, there is a growing interest in leveraging model predictive control (MPC). MPC is proven to have the advantages of addressing the impedance mismatch issue, which leads to system instability and oscillations, owing to its constant handling, multivariable control, predictive capabilities, and optimization-based control. Nevertheless, the generalized MPC faces some technical challenges as it involves intricate enumeration and operations in switching state selection and observer design, thereby increasing computational complexity. Moreover, issues such as variable switching frequency and a lack of protection mechanisms impede its widespread application. To overcome these …

Resonant and soft-switching converters

Authors

Muhammad H Rashid,Shu Yuen Ron Hui,Henry Shu-Hung Chung,Sreedhar Madichetty,NB Shanthi Kumar,B Mohan Krishna

Published Date

2024/1/1

Advances in power electronics in the last few decades have led to not only just improvements in power devices but also new concepts in converter topologies, modulations, and control strategies. In the 1970s, conventional pulse-width modulation (PWM) power converters were operated in a switched-mode operation. Due to the nonideal switching characteristics, power switches have to switch their currents within the turn-on and turn-off times under hard-switching conditions, causing undesired voltage and current stresses. More importantly, hard switching would cause high power and heat dissipation, introducing many reliability problems. To reduce the switching losses and improve the conversion efficiency, various resonant and soft-switching techniques have been proposed and widely used in various power electronic applications. The basic concept is to introduce an extra circuit, use parasitic elements, and/or …

A Galvanic-Isolated Automatic Equalization Charging System for Series-Connected Cells or Battery Strings

Authors

Ruihong Zhang,Shaocong Wang,Zheng Cao,Henry Shu-Hung Chung

Journal

IEEE Transactions on Industrial Electronics

Published Date

2024/4/19

Conventional battery equalization methods typically have high costs and complex control with a large number of switches. Therefore, a galvanic-isolated equalization charging system for series-connected cells or battery strings to equalize the battery voltage automatically during the charging process is proposed in this article. Based on the rate of change of the current passing through the inductor being directly proportional to the voltage drop across an inductor, the batteries under different initial voltage conditions can be charged to a desired uniform voltage level by supplying different corresponding continuous currents to batteries without the need for any sensor and any control. An experimental prototype for six series-connected battery strings was built to validate the balance performance of the proposed automatic equalization charging system.

Active Damping of LLCL‐Filter Resonance Based on LC‐Trap Voltage or Current Feedback

Authors

Henry S Chung,Yuanbin He,Min Huang,Weimin Wu,Frede Blaabjerg

Published Date

2023

The principle and design of the LLCL filter are introduced in Chapter 3. In addition, the design and modeling of passive damped grid‐connected inverters are investigated in Chapters 5 and 6. In the previous chapters, we also show that the LLCL filter is emerging into grid‐connected converters owing to its smaller size compared to the conventional LCL filter but is still burdened by resonance complications when used with a grid converter. Hence, an LLCL‐filtered converter must be passively or actively damped. Active damping is presently more efficient and can easily be realized by feeding back a state variable. For the LCL filter, the variable is usually the middle capacitor current. However, with computational delays, a simple proportional damper cannot be used with the capacitor current. Instead, a high‐pass damper must be used, which may cause undesired noise complications depending on the operating …

Modeling and Suppressing Conducted Electromagnetic Interference Noise for LCL/LLCL‐Filtered Single‐Phase Transformerless Grid‐Connected Inverter

Authors

Henry S Chung,Yuanbin He,Min Huang,Weimin Wu,Frede Blaabjerg

Published Date

2023

For a transformerless grid‐connected inverter (GCI) using PWM technology, the suppression of electromagnetic interference (EMI) noise is important when designing its output filter. This chapter describes a method for effective suppression of conducted EMI noise for a single‐phase GCI with an LCL/LLCL filter. First, the conducted EMI noise (including common mode [CM] and differential mode [DM] EMI noise) is analyzed. Next, an improved LLCL filter topology is proposed for GCI using discontinuous unipolar pulse width modulation (DUPWM) to meet the EMI noise requirements of Comité International Spécial des Perturbations Radioélectriques (CISPR) Class A. The design of filter parameters is given in detail. Similarly, when the GCI uses bipolar pulse width modulation (BPWM), a simple DM EMI suppressor for LLCL‐filtered GCI is proposed to effectively suppress the DM EMI noise with minimum additional …

An ANN-based output-error-driven incremental model predictive control for buck converter against parameter variations

Authors

Yangxiao Xiang,Henry Shu-Hung Chung,Ruihua Shen,Alan Wai-lun Lo

Journal

IEEE Journal of Emerging and Selected Topics in Power Electronics

Published Date

2023/3/6

DC/DC buck converters have been widely applied in the power processing of distributed energy resources (DERs) penetrated DC microgrid. Model predictive control (MPC) provides optimal control for the buck converter, but it often requires multiple sensors or complex observers to realize zero-steady-state-error control against parameter variations. An output-error-driven incremental MPC (OEDIMPC) for buck converter is proposed in this paper. Different from the traditional concept of calculating the optimal duty cycle, the proposed MPC calculates the optimal rate of change of the duty cycle by using a reduced-state output-error-driven prediction model. As a result, the OEDIMPC achieves zero-steady-state-error control against parameter variations, including load value, input voltage, output inductor, and output capacitor, with significantly improved dynamic performance and minimal sensor and observer …

UHF RFID Antenna Sensor System Using Optimal Power-oriented Setup-independent Technique

Authors

Xu Zhang,Han-Xiong Li,Henry Shu-hung Chung

Journal

IEEE Transactions on Antennas and Propagation

Published Date

2023/9/29

Ultrahigh-frequency radio frequency identification (UHF RFID) with a transducer-integrated antenna offers a cost-effective sensing solution for industrial applications. However, the analog backscattered signal contains the coupling effects between the antenna’s nearby environment and the unknown measurement setup, such as mutual distance and orientation between the read/write device (RWD) and sensor tags, and line-of-sight obstruction, which affects measurement accuracy. This article proposes an optimal power-oriented setup-independent technique that utilizes commercially self-tuning RFID tags to extract the environment in the vicinity of the antenna, independent of the measurement setup. The concept is based on an observation that the level of the radiated power of the RWD and the received power of the self-tuning RFID IC are linearly regressed. The condition of the environment is identified by the self …

A Novel Online Grid Impedance Measurement Method Based on Injecting Third Harmonic Voltage

Authors

Yanqi Cheng,Weimin Wu,Mohamed Orabi,Koutroulis Eftychios,Henry Chung,Frede Blaabjerg

Published Date

2023/10/29

Under grid-connected conditions, the adaptive control of the inverter can improve the stability of the system, as long as the grid impedance can be detected online quickly and accurately. The demerits of traditional active grid impedance measurement methods are complex data acquisition and processing, usually involving discrete Fourier transform (DFT), and the injected interference may deteriorate the power quality. In order to reduce the amount of calculation and minimize the impact on the operation of the inverter, this paper proposes to intermittently inject three cycles of the third harmonic signal into the inverter. Then the current and voltage variations at the point of common coupling (PCC) can be extracted through the Kalman filter, and the grid impedance can be estimated. The proposed method alleviates the total harmonic distortion produced by the continuous signal injection in the existing method, reduces …

Robust Impedance‐Based Design of LLCL‐Filtered Grid‐Connected Inverter against the Wide Variation of Grid Reactance

Authors

Henry S Chung,Yuanbin He,Min Huang,Weimin Wu,Frede Blaabjerg

Published Date

2023

The effect of inductive grid impedance variation on the stability of digitally controlled grid‐connected inverters with a high‐order (LCL or LLCL) filter has been extensively studied. Note that a distributed power system may contain a capacitive load, a power factor correction (PFC) capacitor, and a long cable. During the design of grid‐connected inverters, the effects of the equivalent grid reactance, including both inductive and capacitive impedances, on the stability of the system must be addressed. Nevertheless, to the best of our knowledge, the detailed parameter design method of the LCL‐ or LLCL‐filter‐based grid‐connected inverter has not yet been introduced, although the capacitive grid impedance is addressed. In this study, using passivity‐based analyses, a detailed stability study on the LLCL‐filter‐based grid‐connected inverter was performed, while the grid reactance was varied over a wide range. Based …

Design of Passive Damper for LCL/LLCL‐Filtered Grid‐Connected Inverter

Authors

Henry S Chung,Yuanbin He,Min Huang,Weimin Wu,Frede Blaabjerg

Published Date

2023

High‐order passive power filters, such as LCL/LLCL filters, can reduce the amount of magnetic materials and the cost of copper required for grid‐connected inverters; hence, they are becoming increasingly attractive for industrial applications. However, similar to traditional LCL filters, the grid‐connected inverters with LLCL filters still have control challenges, which require active or passive damping measures to suppress resonance between the grid and inverter. For applications under stiff grid conditions, passive damping is usually the first choice because of its simplicity and low cost. This chapter presents a new low‐power passive damping method, which is suitable for LLCL‐filtered grid‐connected inverters. In addition, a practical engineering design standard is presented to determine the optimal damping resistance that is effective for both LCL and LLCL filter‐based systems. The control analyses and power loss …

Experimental Assessment of a Tiny AI-Empowered Output Filter Parameter Extraction Framework for Digital Power

Authors

Kelvin Yi-Wen Hong,Henry Shu-Hung Chung,Yangxiao Xiang,Alan Wai-Lun Lo

Journal

IEEE Access

Published Date

2023/2/13

An experimental assessment of a “plug-and-play” tiny artificial-intelligence-empowered output filter parameter extraction framework for digital power is presented. The framework can be incorporated into an existing digital controller to perform online parameter extraction without adding extra sensors or modifying the power conversion stage. The idea is based on firstly transferring the control from the default control law to the framework, which consists of a predefined control law to perform output regulation for a few switching cycles, then introducing a small-signal perturbation into the control signal, and finally utilizing a long short-term memory (LSTM) network to recognize the dynamic response of the control signal to perform either regression or classification of filter parameters. The LSTM network is trained with a reconfigurable output filter. The proposed framework has been successfully evaluated on a 240W, 100V …

A Novel Single-phase Common-grounded Rectifier Without Electrolytic Capacitor

Authors

Yuhao Yuan,Weimin Wu,Koutroulis Eftychios,Ning Gao,Henry Chung,Frede Blaabjerg,Lixun Zhu,Min Huang

Published Date

2023/9/4

This paper presents a novel non-isolated single-phase power factor correction (PFC) rectifier with active decoupling capability. Firstly, the power decoupling principle is derived and the operating principle of the proposed power decoupling circuit is analyzed. A small DC film capacitor is employed to replace the conventional bulky electrolytic capacitor, while the proposed common-ground structure eliminates leakage current. Furthermore, the implementation of deadbeat control streamlines the control procedure and guarantees the optimal circuit performance. Finally, simulation results are provided to validate the feasibility of the proposed rectifier.

A Nonlinear Inductor-Based MPC Technique for DC Cascaded System Including Constant Power Loads

Authors

Hongjian Lin,Henry Shu-Hung Chung,Ruihua Shen

Published Date

2023/10/29

This paper presents a nonlinear inductor (NI) based model predictive control (MPC) technique for a DC/DC boost converter powering a constant power load (CPL) in a DC cascade system. The integration of the CPL introduces a negative incremental impedance (NII) characteristic at the output, which causes unwanted oscillations in the DC output voltage. This technique improves the stability of DC cascaded systems by employing NI and predictive models that reduce the predictive horizon and computational burden. This results in smoother inductor current, improved steady-state operation, and faster dynamic transition performance. Furthermore, the proposed technique simplifies system design and allows fixed switching frequency operation, making it more practical. In addition, an observer is deigned for obtaining the uncertain value of the CPL. Simulation and experimental results confirm that this technique …

Control Structure and Modulation Techniques of Single‐Phase Grid‐Connected Inverter

Authors

Henry S Chung,Yuanbin He,Min Huang,Weimin Wu,Frede Blaabjerg

Published Date

2023

An overview of the methods for controlling DG‐grid interfacing VSIs with high‐order power filters and their associated challenges have been discussed in Chapter 1. This chapter briefly introduces the basic control structure and modulation techniques for single‐phase grid‐connected inverters as part of future studies. The single‐phase grid‐inverter can be implemented in a natural frame and synchronous rotating frame. For a double‐stage inverter, the Maximum Power Point Tracking (MPPT) controls the boost ratio of the DC/DC converter, and the DC‐link voltage is controlled as an outer loop by the inverter. If the DC voltage is high enough, MPPT directly controls the AC current as a single‐stage inverter. Different modulation methods for single‐phase inverters are also reported in this chapter based on three‐level and two‐level modulations. A comparison of the spectra of PWM output voltage with unipolar and …

Wideband series harmonic voltage compensator using look-ahead state trajectory prediction for network stability enhancement and condition monitoring

Authors

Jacky Chun-Tak Lai,Henry Shu-Hung Chung,Yuanbin He,Weimin Wu,Frede Blaabjerg

Journal

IEEE Transactions on Power Electronics

Published Date

2023/1/4

A wideband series harmonic voltage compensator (WSHVC) with an operating bandwidth of 10 kHz for microgrids with a plurality of grid-connected inverters (GCIs) is proposed. It generates a voltage to compensate for high-frequency harmonic voltage at the point of common coupling (PCC), resulting in a virtually zero high-frequency impedance at the aggregate output of the GCIs and, thus improving system stability. The generation of the harmonic voltage is based on predicting the state trajectory of the WSHVC after a switching period per half-switching cycle to determine the moment at which the switches in the WSHVC change their states. The PCC impedance and the equivalent impedance of the GCI network are extracted by analyzing the system response after injecting the entire system with particle-swarm-optimization (PSO) optimized multisine power disturbances. Therefore, system stability is predicted. The …

Zero-Sequence Voltage Injection-Based Grid Impedance Estimation Method for Three-Phase Four-Wire DC/AC Grid-Connected Inverter

Authors

Yanqi Cheng,Weimin Wu,Yong Yang,Eftichios Koutroulis,Henry Shu-Hung Chung,Marco Liserre,Frede Blaabjerg

Journal

IEEE Transactions on Industrial Electronics

Published Date

2023/8/23

In this article, a novel method based on zero-sequence voltage injection to estimate grid impedance is proposed. The target of the proposed method is to inject a third harmonic before space vector pulse width modulation in order to generate zero-sequence voltage on the output side of the inverter. Then, the voltage response of the point of common coupling is measured to estimate the grid impedance. The main advantage of this method is that it minimizes the impact on the operation of the grid-connected inverter, without complex signal processing calculations. A three-phase four-wire dc–ac inverter configuration interconnected with the electric grid has been used to verify the effectiveness of the proposed method experimentally.

A Single-Source-Based Non-Isolated Micro-Inverter with Active Power Decoupling

Authors

Qianqian Li,Weimin Wu,Mohammed Orabi,Frede Blaabjerg,Henry Chung

Published Date

2023/10/16

In order to mitigate the negative effect of multi-frequency ripple power, a non-isolated micro-inverter with active power decoupling has been proposed in recent years, which shows some potential advantages, in terms of low cost, fewer switches, high efficiency, and a brief system control strategy. However, it has two independent PV panel input dc sources, which may be asymmetrical in realistic PV systems, resulting in a decrease in the power generation capacity of the whole system. To address this problem, an improved non-isolated micro-inverter topology with active power decoupling is proposed in this paper. Similar to the conventional micro-inverter, it can effectively suppress the common-mode leakage current. Different from the conventional micro-inverter topology, it uses a single PV panel input dc source and achieves positive and negative half-line cycle equivalent dc sources through two split-bus capacitors …

An LLCL Power Filter for Single‐Phase Grid‐Connected Inverter

Authors

Henry S Chung,Yuanbin He,Min Huang,Weimin Wu,Frede Blaabjerg

Published Date

2023

This chapter presents a novel topology of higher‐order power filter, named as LLCL filter, for single‐phase grid‐connected voltage‐source inverter. A small inductor is inserted in the branch loop of the capacitor in the traditional LCL filter to form a series resonant circuit at the switching frequency. In particular, it can attenuate the switching frequency current ripple component better than the LCL filter thereby reducing the total inductance and volume. In addition, the parametric design criteria for the proposed LLCL filter are also discussed. Experiments on the conventional LCL filter and the proposed LLCL filter are carried out on a 1.8 kW single‐phase grid‐connected inverter prototype. Results are compared, analyzed and discussed, and evaluated accordingly.

See List of Professors in Henry Chung University(City University of Hong Kong)

Henry Chung FAQs

What is Henry Chung's h-index at City University of Hong Kong?

The h-index of Henry Chung has been 41 since 2020 and 79 in total.

What are Henry Chung's top articles?

The articles with the titles of

Open-Circuit Fault Diagnosis and Fault-Tolerant Control for a Coupled-Inductor-Based Aalborg Inverter

Achieving Fast Dynamic Response and Output Filter Condition Monitoring in Hybrid PWM Inverters Using a Low-Computational State Trajectory Prediction Algorithm Incorporating …

Enhancing Stability of DC Cascaded Systems with CPLs using MPC Combined with NI And Accounting for Parameter Uncertainties

Resonant and soft-switching converters

A Galvanic-Isolated Automatic Equalization Charging System for Series-Connected Cells or Battery Strings

Active Damping of LLCL‐Filter Resonance Based on LC‐Trap Voltage or Current Feedback

Modeling and Suppressing Conducted Electromagnetic Interference Noise for LCL/LLCL‐Filtered Single‐Phase Transformerless Grid‐Connected Inverter

An ANN-based output-error-driven incremental model predictive control for buck converter against parameter variations

...

are the top articles of Henry Chung at City University of Hong Kong.

What are Henry Chung's research interests?

The research interests of Henry Chung are: Power Electronics

What is Henry Chung's total number of citations?

Henry Chung has 23,067 citations in total.

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