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Huai Wang

Bio: Huai Wang is an academic researcher from Aalborg University. The author has contributed to research in topics: Capacitor & Power electronics. The author has an hindex of 38, co-authored 328 publications receiving 7480 citations. Previous affiliations of Huai Wang include Yangtze University & City University of Hong Kong.


Papers
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Journal ArticleDOI
TL;DR: This review serves to provide a clear picture of the state-of-the-art research in this area and to identify the corresponding challenges and future research directions for capacitors and their dc-link applications.
Abstract: DC-link capacitors are an important part in the majority of power electronic converters which contribute to cost, size and failure rate on a considerable scale. From capacitor users' viewpoint, this paper presents a review on the improvement of reliability of dc link in power electronic converters from two aspects: 1) reliability-oriented dc-link design solutions; 2) conditioning monitoring of dc-link capacitors during operation. Failure mechanisms, failure modes and lifetime models of capacitors suitable for the applications are also discussed as a basis to understand the physics-of-failure. This review serves to provide a clear picture of the state-of-the-art research in this area and to identify the corresponding challenges and future research directions for capacitors and their dc-link applications.

882 citations

Journal ArticleDOI
TL;DR: The performance of power electronic systems, especially in terms of efficiency and power density, has continuously improved by the intensive research and advancements in circuit topologies, control schemes, semiconductors, passive components, digital signal processors, and system integration technologies.
Abstract: A new era of power electronics was created with the invention of the thyristor in 1957. Since then, the evolution of modern power electronics has witnessed its full potential and is quickly expanding in the applications of generation, transmission, distribution, and end-user consumption of electrical power. The performance of power electronic systems, especially in terms of efficiency and power density, has been continuously improved by the intensive research and advancements in circuit topologies, control schemes, semiconductors, passive components, digital signal processors, and system integration technologies.

689 citations

Journal ArticleDOI
TL;DR: In this article, the three major aspects of power electronics reliability are discussed, respectively, which cover physics-of-failure analysis of critical power electronic components, state-ofthe-art design for reliability process and robustness validation, and intelligent control and condition monitoring to achieve improved reliability under operation.
Abstract: Power electronics has progressively gained an important status in power generation, distribution, and consumption. With more than 70% of electricity processed through power electronics, recent research endeavors to improve the reliability of power electronic systems to comply with more stringent constraints on cost, safety, and availability in various applications. This paper serves to give an overview of the major aspects of reliability in power electronics and to address the future trends in this multidisciplinary research direction. The ongoing paradigm shift in reliability research is presented first. Then, the three major aspects of power electronics reliability are discussed, respectively, which cover physics-of-failure analysis of critical power electronic components, state-of-the-art design for reliability process and robustness validation, and intelligent control and condition monitoring to achieve improved reliability under operation. Finally, the challenges and opportunities for achieving more reliable power electronic systems in the future are discussed.

531 citations

Journal ArticleDOI
TL;DR: In this article, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults is explored in order to map future challenges, and control strategies with reactive power injection are also discussed.
Abstract: Transformerless photovoltaic (PV) inverters are going to be more widely adopted in order to achieve high efficiency, as the penetration level of PV systems is continuously booming. However, problems may arise in highly PV-integrated distribution systems. For example, a sudden stoppage of all PV systems due to anti-islanding protection may contribute to grid disturbances. Thus, standards featuring with ancillary services for the next-generation PV systems are under a revision in some countries. The future PV systems have to provide a full range of services as what the conventional power plants do, e.g., low-voltage ride-through (LVRT) under grid faults and grid support service. In order to map future challenges, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults is explored in this paper. Control strategies with reactive power injection are also discussed. The selected inverters are the full-bridge (FB) inverter with bipolar modulation, the FB inverter with dc bypass, and the Highly Efficient and Reliable Inverter Concept (HERIC). A 1-kW single-phase grid-connected PV system is analyzed to verify the discussions. The tests confirmed that, although the HERIC inverter is the best candidate in terms of efficiency, it is not very particularly feasible in case of a voltage sag. The other two topologies are capable of providing reactive current during LVRT. A benchmarking of those inverters is also provided in this paper, which offers the possibility to select appropriate devices and to further optimize the transformerless system.

307 citations

Journal ArticleDOI
TL;DR: The three distinctive life-cycle phases, design, control, and maintenance are correlated with one or more tasks to be addressed by AI, including optimization, classification, regression, and data structure exploration.
Abstract: This article gives an overview of the artificial intelligence (AI) applications for power electronic systems. The three distinctive life-cycle phases, design, control, and maintenance are correlated with one or more tasks to be addressed by AI, including optimization, classification, regression, and data structure exploration. The applications of four categories of AI are discussed, which are expert system, fuzzy logic, metaheuristic method, and machine learning. More than 500 publications have been reviewed to identify the common understandings, practical implementation challenges, and research opportunities in the application of AI for power electronics. This article is accompanied by an Excel file listing the relevant publications for statistical analytics.

287 citations


Cited by
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Journal ArticleDOI

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08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

01 Nov 2000
TL;DR: In this paper, the authors compared the power density characteristics of ultracapacitors and batteries with respect to the same charge/discharge efficiency, and showed that the battery can achieve energy densities of 10 Wh/kg or higher with a power density of 1.2 kW/kg.
Abstract: The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

2,437 citations

01 Sep 2010

2,148 citations

Journal ArticleDOI
01 Jan 1977-Nature
TL;DR: Bergh and P.J.Dean as discussed by the authors proposed a light-emitting diode (LEDD) for light-aware Diodes, which was shown to have promising performance.
Abstract: Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

1,560 citations