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.

A Temperature-dependent Thermal Model of Silicon Carbide MOSFET Module for Long-term Reliability Assessment

Abstract: The silicon carbide (SiC) device is by far the most promising technology for the next-generation power electronic systems. However, the wide application of SiC device is inhibited by its reliability uncertainties, and a comprehensive SiC thermal model, which considers the temperature-dependency, is still missing for long-term reliability assessment. Thus, this paper proposes a temperature-dependent thermal model of SiC MOSFET module, which is composed of RC lumped elements and it is suitable for long-term reliability analysis. To begin with, the temperature-dependent thermal properties of the packaging materials (including SiC) are fully investigated. Then, the finite element method (FEM) based analysis containing temperature-dependency is utilized to extract both the self-heating and cross-coupling thermal impedances. Finally, a diagram of the RC lumped temperature-dependent thermal model is proposed, which is verified using a 3-level active neutral-point clamped (3-L ANPC) study case by performing its PLECS simulation.

A Mission-Profile-Based Tool for the Reliability Evaluation of Power Semiconductor Devices in Hybrid Electric Vehicles

Abstract: Due to increasing environmental concerns, hybrid electric vehicles (HEVs) are gaining more and more attention. However, the reliability aspect performance of the power electronic system can be a limiting factor, and can increase the overall life-cycle cost of the vehicle if not properly designed. Consequently, in order to fulfil the stringent reliability demands, and cost constraints of the automotive sector, special emphasis is placed during early development stages on evaluating the reliability of power converters. Thus, the need for realistic and fast reliability analysis of power semiconductor devices arises. As a result, a mission-profile-based reliability assessment tool platform for power electronic systems is proposed in this paper. The reliability evaluation procedure and the proposed tool are demonstrated on a HEV application study-case.

A single position loop control strategy for high-speed voice coil motor based on active disturbance rejection control

Abstract: To improve the dynamic performance of voice coil motor, a single position loop control method based on active disturbance rejection control is proposed in this paper. The feedback law is sufficiently analyzed and well designed considering both sinusoidal input and step reference input. Moreover, stability analysis is conducted on the basis of a state-space model and Routh-Hurwitz criterion, which is proved to be stable and convergent under proper parameter arrangement. Further, simulation and experimental validation indicate that the proposed control strategy has faster step response and better tracking accuracy compared with traditional three-loop PI controller with only one eighth of settling time and less than half of the tracking error compared to PI controller.

Parasitics of Orthocyclic Windings in Inductors and Transformers

Abstract: Orthocyclic winding in magnetic components is common in both laboratory prototyping and mass production, especially for round wires with curved edges. However, its impact on winding parasitics, i.e., winding capacitance, ac resistance, and leakage inductance, has not been systematically investigated yet. Omission or inaccurate calculation of these parameters leads to current ringing, additional losses, and even abnormal operations. In this article, three modified formulas for parasitics of orthocyclic windings are proposed, and the impacts of orthocyclic windings are comprehensively studied. Magnetic field distortion and air-gap effect are analyzed and compensated. The formulas are verified by finite-element method (FEM) simulation and experimental results. Finally, normal and orthocyclic windings are compared, and conclusions are listed to illustrate the impact of orthocyclic windings on parasitics.

I and i

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 …

Ultracapacitors: Why, How, and Where is the Technology

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.

Light-emitting diodes

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.