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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
09 Nov 2020
TL;DR: In this article, a capacitance bank thermal impedance model considering the coupling between capacitors is proposed, and experimental characterizations are performed on 450 V/5.3 mF electrolytic capacitors.
Abstract: This paper proposes a capacitor bank thermal impedance model considering the coupling between capacitors. FEM simulations and experimental characterizations are performed on 450 V/5.3 mF electrolytic capacitors. The comparative results verify the effectiveness of the proposed thermal model.
Proceedings ArticleDOI
01 Sep 2019
TL;DR: In this article, an instantaneous loss and thermal modeling procedure for metal oxide varistors under a standard current surge mission profile is proposed, and the experimental measurements are in well agreement with the simulation results, and thus, providing an initial validation of the proposed modeling procedure.
Abstract: Because of their crucial role in protecting power electronic equipment against over-voltages and transients, metal oxide varistors (MOV) represent a key component of the electrical system. Although improper heat dissipation and internal temperature rises can lead to a significant decrease in performance or even to a wear-out failure of the MOV, there are very few studies in the literature describing the thermal modeling of varistors. Thus, in this paper, an instantaneous loss and thermal modeling procedure for MOV under a standard current surge mission profile is proposed. Initially, the specification and characteristics of a study-case varistor are presented, followed by a detailed description of the electro-thermal modeling procedure. Afterwards, the thermal behavior of the MOV is investigated and the differences between the heating and cool-down thermal models are highlighted. Finally, in order to validate the proposed electrothermal models, the temperature of the varistor is measured with an infrared camera. The experimental measurements are in well agreement with the simulation results, and thus, providing an initial validation of the proposed modeling procedure.
Proceedings ArticleDOI
15 May 2022
TL;DR: In this paper , the IGBT knee voltage at a low conduction current of tens of milliamps is explored as a novel indicator and named IGBT knees voltage, which is independent of the operating current and package-level degradation of IGBT modules.
Abstract: Thermo-sensitive electrical parameters (TSEPs) are widely employed in the junction temperature estimation of insulated gate bipolar transistor (IGBT) modules. In this paper, the IGBT on-state voltage at a low conduction current of tens of milliamps is explored as a novel indicator and named IGBT knee voltage. Unlike existing TSEPs, this specific on-state voltage is independent of the operating current and package-level degradation of IGBT modules and has a monotonic thermal dependence. As a result, the junction temperature can be estimated based on the IGBT on-state saturation voltage information without the need for synchronized current sampling and dedicated degradation calibration. A single-phase inverter case study is presented to demonstrate the proposed method. The experimental results verify the monotonic dependence between the IGBT knee voltage and junction temperature.
Proceedings ArticleDOI
14 Jun 2021
TL;DR: Based on the measured efficiency data obtained from the built prototypes, the reliability analysis results indicate that under the same design specifications and criteria, the accumulated failure of the IPOS bridgeless is much lower than that of the conventional boost PFC converter.
Abstract: Bridgeless power factor correction (PFC) converters are gaining popularity in recent years mainly for the efficiency superiority over their conventional topology counterparts. However, the quantitative reliability analysis of the bridgeless topologies in the wear-out region is missing and their reliability performances compared with the conventional one are unknown. Thus, based on the telecom applications with a representative mission profile in a rural area, this paper employs a mission profile-based reliability analysis approach to estimate the failure probability of an input-parallel output-series (IPOS) bridgeless boost PFC converter, along with the conventional one. Based on the measured efficiency data obtained from the built prototypes, the reliability analysis results indicate that under the same design specifications and criteria, the accumulated failure of the IPOS bridgeless is 0.27% within 20 years of operation, much lower than that (2.06%) of the conventional boost PFC converter.

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