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Two-Phase Interleaved Buck Converter with a new Digital Self-Oscillating Modulator
Lars T. Jakobsen,Michael A. E. Andersen 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-
This paper presents a new Digital Self-Oscillating Modulator (DiSOM) for DC/DC converters. The DiSOM modulator alllows the digital control algorithm to sample the output voltage at a sampling frequency higher than the converter switching frequency. This enables higher control loop bandwidth than for traditional digital PWM modulators given a certain switching frequency. A synchronised version of the DiSOM modulator is derived for interleaved converters. A prototype interleaved Buck converter for Point of Load applications has been designed and built to test the performance of DiSOM modulator. The DiSOM modulator and a digital control algorithm have been implemented in an FPGA. Experimental results show that the converter has a very fast transient response when a loadstep is applied to the output. For a loadstep of 50% of nominal output current the output voltage overshoot is less than 2.5% of the nominal output voltage and the settling time is just 8 switching periods.
<i>SPITZER</i>PARALLAX OF OGLE-2015-BLG-0966: A COLD NEPTUNE IN THE GALACTIC DISK
Street, R. A.,Udalski, A.,Novati, S. Calchi,Hundertmark, M. P. G.,Zhu, W.,Gould, A.,Yee, J.,Tsapras, Y.,Bennett, D. P.,Jørgensen, U. G.,Dominik, M.,Andersen, M. I.,Bachelet, E.,Bozza, V.,Bramich, D. M American Astronomical Society 2016 The Astrophysical journal Vol.819 No.2
<P>We report the detection of a cold Neptune m(planet) = 21 +/- 2M(circle plus) orbiting a 0.38M(circle dot) M dwarf lying 2.5-3.3 kpc toward the Galactic center as part of a campaign combining ground-based and Spitzer observations to measure the Galactic distribution of planets. This is the first time that the complex real-time protocols described by Yee et al., which aim to maximize planet sensitivity while maintaining sample integrity, have been carried out in practice. Multiple survey and follow. up teams successfully combined their efforts within the framework of these protocols to detect this planet. This is the second planet in the Spitzer Galactic distribution sample. Both are in the near. to. mid-disk and are clearly not in the Galactic bulge.</P>
Qingnan Li,Michael A. E. Andersen,Ole C. Thomsen 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
Nowadays, efficiency and power density are the most important issues for Power Factor Correction (PFC) converters development. However, it is a challenge to reach both high efficiency and power density in a system at the same time. In this paper, taking a Bridgeless PFC (BPFC) as an example, a useful compromise between efficiency and power density of the Boost inductors on 3.2㎾ is achieved using an optimized design procedure. The experimental verifications based on the optimized inductor are carried out from 300W to 3.2㎾ at 220Vac input.
Marquardt, J.U.,Seo, D.,Andersen, J.B.,Gillen, M.C.,Kim, M.S.,Conner, E.A.,Galle, P.R.,Factor, V.M.,Park, Y.N.,Thorgeirsson, S.S. Elsevier Science Publishers 2014 Journal of hepatology Vol.60 No.2
Background & Aims: Human hepatocarcinogenesis is as a multi-step process starting from dysplastic lesions to early carcinomas (eHCC) that ultimately progress to HCC (pHCC). However, the sequential molecular alterations driving malignant transformation of the pre-neoplastic lesions are not clearly defined. This lack of information represents a major challenge in the clinical management of patients at risk. Methods: We applied next-generation transcriptome sequencing to tumor-free surrounding liver (n=7), low- (n=4) and high-grade (n=9) dysplastic lesions, eHCC (n=5) and pHCC (n=3) from 8 HCC patients with hepatitis B infection. Integrative analyses of genetic and transcriptomic changes were performed to characterize the genomic alterations during hepatocarcinogenesis. Results: We report that changes in transcriptomes of early lesions including eHCC were modest and surprisingly homogenous. Extensive genetic alterations and subsequent activation of prognostic adverse signaling pathways occurred only late during hepatocarcinogenesis and were centered on TGFβ, WNT, NOTCH, and EMT-related genes highlighting the molecular diversity of pHCC. We further identify IGFALS as a key genetic determinant preferentially down-regulated in pHCC. Conclusions: Our results define new hallmarks in molecular stratification and therapy options for patients at risk for HCC, and merit larger prospective investigations to develop a modified clinical-decision making algorithm based on the individualized next-generation sequencing analyses.
Isolated Boost Converter with Bidirectional Operation for Supercapacitor Applications
Juan C. Hernandez,Maria C. Mira,Gokhan Sen,Ole C. Thomsen,Michael A. E. Andersen 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.4
This paper presents an isolated bidirectional dc/dc converter based on primary parallel isolated boost converter (PPIBC). This topology is an efficient solution in low voltage high power applications due to its ability to handle high currents in the low voltage side. In this paper, the converter has been modeled using non-ideal components and operated without any additional circuitry for startup using a digital soft-start procedure. Simulated and measured loop gains have been compared for the validity of the model. On-the-fly current direction change has been achieved with a prototype interconnecting two battery banks. A second prototype has been constructed and tested for supercapacitor operation in constant power charge mode.
Isolated Boost Converter with Bidirectional Operation for Supercapacitor Applications
Hernandez, Juan C.,Mira, Maria C.,Sen, Gokhan,Thomsen, Ole C.,Andersen, Michael A.E. The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.4
This paper presents an isolated bidirectional dc/dc converter based on primary parallel isolated boost converter (PPIBC). This topology is an efficient solution in low voltage high power applications due to its ability to handle high currents in the low voltage side. In this paper, the converter has been modeled using non-ideal components and operated without any additional circuitry for startup using a digital soft-start procedure. Simulated and measured loop gains have been compared for the validity of the model. On-the-fly current direction change has been achieved with a prototype interconnecting two battery banks. A second prototype has been constructed and tested for supercapacitor operation in constant power charge mode.
Research of Gap Filler Material in the GaN Transistor Thermal Management
Bainan Sun,Niels Elkjær Iversen,Zhe Zhang,Michael A.E. Andersen 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
High power dissipation in the small package Gallium Nitride (GaN) transistor calls for challenge in thermal design. This paper compares the impact of different gap filler materials in the GaN transistor power dissipation. Simulation and experimental results are given to reveal the maximum power dissipated in each setup, which validates the critical impact of gap filler material in thermal design. The developed test procedure and thermal model are elaborated, which can be easily applied to the estimation of thermal management in other GaN transistor applications.