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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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Proceedings ArticleDOI
10 Oct 2021
TL;DR: In this article, a comparative study on three converter-level measurement circuits is given in terms of hardware design, operational performance, and practical implementation, which guides the selection and design of suitable measurement circuit for different applications.
Abstract: The on-state voltage is a key characteristic parameter and relative to the health condition and junction temperature of power semiconductor devices. Hence, it is widely used to evaluate the reliability and realize the predictive maintenance of power devices. Recently, three converter-level measurement circuits are proposed, capable of extracting the on-state voltage of all power devices in a power converter with one circuit only. In this paper, a comparative study on these three converter-level circuits is given in terms of hardware design, operational performance, and practical implementation, which guides the selection and design of suitable measurement circuit for different applications. The comparisons are illustrated with theoretical analyses and experimental results.

3 citations

Proceedings ArticleDOI
27 May 2019
TL;DR: An analysis and design method for estimating the lifetime performance of multiple capacitor bank designs and is able to provide crucial information to the designer, such as the compromise between lifetime, cost, and volume.
Abstract: The development of a tool is presented for optimizing dc-link capacitors design in PV inverters. Reliability of power converters is well known to be one of the bottlenecks for decreasing the cost of renewable energy systems. Thus, this paper proposes an analysis and design method for estimating the lifetime performance of multiple capacitor bank designs. A case study is performed in a single-stage single-phase PV inverter. A realistic mission profile is used and built with real weather data and combined with a PV model in order to obtain the relevant values of power processing throughout a 1-year operation. A capacitor electro-thermal modeling is done in order to evaluate their operating conditions in time. Results show that the proposed tool is able to provide crucial information to the designer, such as the compromise between lifetime, cost, and volume.

3 citations

Journal ArticleDOI
TL;DR: Results reveal that the estimated intrinsic parameters from large-signal dynamic characteristic correlate with the observed health status of the tested panels.

3 citations

Proceedings ArticleDOI
15 Mar 2020
TL;DR: In this article, a hierarchical decomposition method is proposed to do the system-level thermal modeling of the MMC At sub-Module(SM) level, e.g., junction/hotspot-to-local ambient thermal model of devices is established, where thermal cross-coupling effects among different devices in the SM are considered At converter-level, thermal model is obtained to depict mutual European influences among the SMs in MMC A 15-kVA MMC prototype provides the experimental verifications at last
Abstract: In the thermal analysis of a Modular Multilevel Converter (MMC) system, one of the challenges is to model the heat sources and thermal paths across large spatial scales, ie, from a tiny power semiconductor chip at square millimeters to the whole converter system up to several thousand cubic meters Without good understanding of the dissimilarity of thermal behaviors under different spatial scales, conventional thermal models usually lead to either considerable modeling errors or heavy computational burden In this paper, a hierarchical decomposition method is proposed to do the system-level thermal modeling of the MMC At Sub-Module(SM) level, ethe junction/hotspot-to-local ambient thermal model of devices is established, where Thermal Cross-Coupling (TCC) effects among different devices in the SM are considered At converter-level, thermal model is obtained to depict mutual European influences Unionamong the SMs in the MMC A 15-kVA MMC prototype provides the experimental verifications at last

3 citations

Proceedings ArticleDOI
15 Mar 2020
TL;DR: Both theoretical and experimental results indicate the feasibility of the proposed method for DC-DC converter applications, and it features non-invasive, without additional hardware and easily implementing.
Abstract: In this work, a duty cycle ratio-based condition monitoring method is proposed for the MOSFETs in digitally-controlled DC-DC power converters It is demonstrated and proved with an example of buck converter Theoretically, the average value of duty cycle ratio is positively related to the on-state resistance of MOSFET Therefore, the proposed method enables the condition monitoring of the degradation of MOSFET The impact of other factors, such as input voltage, temperature, loading and other components in buck converter, on the duty cycle ratio is also investigated Experimental tests are performed in different situations Both theoretical and experimental results indicate the feasibility of the proposed method for DC-DC converter applications Compare to the conventional methods, the proposed method features non-invasive, without additional hardware and easily implementing

3 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